diff --git a/src/printer.js b/src/printer.js
index a86cc6bf..6d48380f 100644
--- a/src/printer.js
+++ b/src/printer.js
@@ -769,7 +769,7 @@ function genericPrintNoParens(path, options, print) {
 
     var args = n.arguments;
 
-    if (args && args.length > 0) {
+    if (args) {
       parts.push(printArgumentsList(path, options, print));
     }
 
diff --git a/tests/annot/__snapshots__/jsfmt.spec.js.snap b/tests/annot/__snapshots__/jsfmt.spec.js.snap
index 8dd64d59..5095fdef 100644
--- a/tests/annot/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/annot/__snapshots__/jsfmt.spec.js.snap
@@ -158,7 +158,7 @@ function foo() {
   let myClassInstance: MyClass = mk();
   // ok (no confusion across scopes)
   function mk() {
-    return new MyClass;
+    return new MyClass();
   }
 
   class MyClass {} // looked up above
diff --git a/tests/arrays/__snapshots__/jsfmt.spec.js.snap b/tests/arrays/__snapshots__/jsfmt.spec.js.snap
index 556ad7ba..56b529b4 100644
--- a/tests/arrays/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/arrays/__snapshots__/jsfmt.spec.js.snap
@@ -89,7 +89,7 @@ arr[day] = 0;
 (arr[day]: string); // error: number ~> string
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 var arr = [];
-var day = new Date;
+var day = new Date();
 
 // Date instances are numeric (see Flow_js.numeric) and thus can index into
 // arrays.
diff --git a/tests/async/__snapshots__/jsfmt.spec.js.snap b/tests/async/__snapshots__/jsfmt.spec.js.snap
index 0ad2a98a..564deaeb 100644
--- a/tests/async/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/async/__snapshots__/jsfmt.spec.js.snap
@@ -182,7 +182,7 @@ class C {
 var e = async function() {};
 var et = async function<T>(a: T) {};
 
-var n = new async function() {};
+var n = new async function() {}();
 
 var o = { async m() {} };
 var ot = { async m<T>(a: T) {} };
@@ -484,7 +484,7 @@ var et = async function<T>(a: T) {
 
 var n = new async function() {
   await 1;
-};
+}();
 
 var o = {
   async m() {
diff --git a/tests/binding/__snapshots__/jsfmt.spec.js.snap b/tests/binding/__snapshots__/jsfmt.spec.js.snap
index 7bb830c0..bbe81b8a 100644
--- a/tests/binding/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/binding/__snapshots__/jsfmt.spec.js.snap
@@ -876,11 +876,11 @@ function f5() {
 //
 var x: C;
 // ok
-var y = new C;
+var y = new C();
 // error: let ref before decl from value position
 class C {}
 
-var z: C = new C;
+var z: C = new C();
 // ok
 // --- vars ---
 // it\'s possible to annotate a var with a non-maybe type,
diff --git a/tests/bom/__snapshots__/jsfmt.spec.js.snap b/tests/bom/__snapshots__/jsfmt.spec.js.snap
index 3e51773b..7250be84 100644
--- a/tests/bom/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/bom/__snapshots__/jsfmt.spec.js.snap
@@ -70,7 +70,7 @@ for (let [x, y]: [number, number] of a.entries()) {} // incorrect
 /* @flow */
 
 // constructor
-const a: FormData = new FormData;
+const a: FormData = new FormData();
 // correct
 new FormData(\"\");
 // incorrect
@@ -116,11 +116,11 @@ a.set(\"bar\", new File([], \"q\"), \"x\");
 // correct
 a.set(\"bar\", new File([], \"q\"), 2);
 // incorrect
-a.set(\"bar\", new Blob);
+a.set(\"bar\", new Blob());
 // correct
-a.set(\"bar\", new Blob, \"x\");
+a.set(\"bar\", new Blob(), \"x\");
 // correct
-a.set(\"bar\", new Blob, 2);
+a.set(\"bar\", new Blob(), 2);
 // incorrect
 // append
 a.append(\"foo\", \"bar\");
@@ -139,11 +139,11 @@ a.append(\"bar\", new File([], \"q\"), \"x\");
 // correct
 a.append(\"bar\", new File([], \"q\"), 2);
 // incorrect
-a.append(\"bar\", new Blob);
+a.append(\"bar\", new Blob());
 // correct
-a.append(\"bar\", new Blob, \"x\");
+a.append(\"bar\", new Blob(), \"x\");
 // correct
-a.append(\"bar\", new Blob, 2);
+a.append(\"bar\", new Blob(), 2);
 // incorrect
 // delete
 a.delete(\"xx\");
@@ -218,7 +218,7 @@ new MutationObserver((arr: Array<MutationRecord>) => true);
 // correct
 new MutationObserver(() => {});
 // correct
-new MutationObserver;
+new MutationObserver();
 // incorrect
 new MutationObserver(42);
 // incorrect
diff --git a/tests/bounded_poly/__snapshots__/jsfmt.spec.js.snap b/tests/bounded_poly/__snapshots__/jsfmt.spec.js.snap
index 82b019c4..851d2f9e 100644
--- a/tests/bounded_poly/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/bounded_poly/__snapshots__/jsfmt.spec.js.snap
@@ -67,7 +67,7 @@ function example<T: { x: number }>(o: T): T {
 var obj1: { x: number, y: string } = example({ x: 0, y: \"\" });
 var obj2: { x: number } = example({ x: 0 });
 
-var c: C<string> = new C;
+var c: C<string> = new C();
 // error, since T = string is incompatible with number
 var q: number = c.qux(0);
 /* 2 more errors, since argument U = number is incompatible with T = string, and
diff --git a/tests/builtins/__snapshots__/jsfmt.spec.js.snap b/tests/builtins/__snapshots__/jsfmt.spec.js.snap
index 5bd1ee42..c2a155cf 100644
--- a/tests/builtins/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/builtins/__snapshots__/jsfmt.spec.js.snap
@@ -32,7 +32,7 @@ function f() {
 }
 
 var Foo = require(\"./genericfoo\");
-var foo = new Foo;
+var foo = new Foo();
 function g() {
   var foo1 = foo.map(function() {
     return \"...\";
@@ -60,7 +60,7 @@ class Foo<T> {
     return this;
   }
   map<U>(callbackfn: () => U): Foo<U> {
-    return new Foo;
+    return new Foo();
   }
   set(x: T): void {}
   get(): T {
diff --git a/tests/class_statics/__snapshots__/jsfmt.spec.js.snap b/tests/class_statics/__snapshots__/jsfmt.spec.js.snap
index bb6b3704..9e4285bd 100644
--- a/tests/class_statics/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/class_statics/__snapshots__/jsfmt.spec.js.snap
@@ -88,11 +88,11 @@ class B extends A {
     B.qux(0); // error
   }
   static create(): A {
-    return new this;
+    return new this();
   }
 
   static badCreate(): number {
-    return new this; // error B ~> number
+    return new this(); // error B ~> number
   }
 }
 
@@ -100,7 +100,7 @@ class C<X> {
   static x: X;
   static bar(x: X) {}
   static create(): C<*> {
-    return new this;
+    return new this();
   }
 }
 
@@ -113,7 +113,7 @@ class D extends C<string> {
 }
 
 var d: C<*> = D.create();
-(new A: typeof A);
+(new A(): typeof A);
 (B: typeof A);
 
 class E {
diff --git a/tests/class_subtyping/__snapshots__/jsfmt.spec.js.snap b/tests/class_subtyping/__snapshots__/jsfmt.spec.js.snap
index 38c9c03d..0842f2b6 100644
--- a/tests/class_subtyping/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/class_subtyping/__snapshots__/jsfmt.spec.js.snap
@@ -26,8 +26,8 @@ var I = require(\"./test.js\");
 
 class C extends I.A {}
 
-var x: I.A = new C;
-var y: I.B = new C;"
+var x: I.A = new C();
+var y: I.B = new C();"
 `;
 
 exports[`test test3.js 1`] = `
@@ -42,7 +42,7 @@ class A<X, Y, Z> {}
 class B extends A<string, number, boolean> {}
 class C<X, Y, Z> extends B {}
 
-var c: C<number, string, Array<boolean>> = new C;
+var c: C<number, string, Array<boolean>> = new C();
 // none of the type args matter
 var a: A<string, number, Array<boolean>> = c; // the third type arg is incorrect"
 `;
@@ -70,7 +70,7 @@ function foo<X>(c: C<X>, x: X) {}
 
 type O = { f: number };
 
-foo((new C: C<O>), { f_: 0 });
+foo((new C(): C<O>), { f_: 0 });
 
 class D extends C<O> {
   bar() {
@@ -78,5 +78,5 @@ class D extends C<O> {
   }
 }
 
-foo(new D, { f_: 0 });"
+foo(new D(), { f_: 0 });"
 `;
diff --git a/tests/class_type/__snapshots__/jsfmt.spec.js.snap b/tests/class_type/__snapshots__/jsfmt.spec.js.snap
index 43878951..9a2e53fc 100644
--- a/tests/class_type/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/class_type/__snapshots__/jsfmt.spec.js.snap
@@ -13,14 +13,14 @@ function bar(x: Class<B>): B {
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 class A {}
 function foo(x: Class<A>): A {
-  return new x; // OK
+  return new x(); // OK
 }
 
 class B {
   constructor(_: any) {}
 }
 function bar(x: Class<B>): B {
-  return new x; // error (too few args)
+  return new x(); // error (too few args)
 }"
 `;
 
@@ -49,9 +49,9 @@ class A {}
 class B extends A {}
 class C {}
 
-check(B, new A);
-check(A, new B);
-check(C, new A);
-check(C, new B);
-check(B, new C);"
+check(B, new A());
+check(A, new B());
+check(C, new A());
+check(C, new B());
+check(B, new C());"
 `;
diff --git a/tests/classes/__snapshots__/jsfmt.spec.js.snap b/tests/classes/__snapshots__/jsfmt.spec.js.snap
index dc2877db..cbf6ec21 100644
--- a/tests/classes/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/classes/__snapshots__/jsfmt.spec.js.snap
@@ -26,7 +26,7 @@ var A = require(\"./A\");
 
 class B extends A {}
 
-let b = new B;
+let b = new B();
 (b.foo: number);
 // error, number !~> function
 module.exports = B;"
@@ -50,7 +50,7 @@ class C extends B {
   foo(x: string): void {}
 }
 
-let c = new C;
+let c = new C();
 (c.foo: number);
 // error, number !~> function
 module.exports = C;"
@@ -63,7 +63,7 @@ new E().x
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 class D {}
 class E {}
-new E.x;"
+new E().x;"
 `;
 
 exports[`test class_shapes.js 1`] = `
@@ -120,7 +120,7 @@ class TestClass {
   c: ?string;
 }
 
-var x = new TestClass;
+var x = new TestClass();
 
 x.a;
 // ok
@@ -144,7 +144,7 @@ class Test2Class extends Test2Superclass {
   b: number; // conflicts with cast to Foo
 }
 
-var z = new Test2Class;
+var z = new Test2Class();
 var w: Foo = z;"
 `;
 
@@ -183,33 +183,33 @@ var alias2: Alias = _Alias.factory(); // error: bad pun
 var Bar = class Foo {
   static factory(): Foo {
     // OK: Foo is a type in this scope
-    return new Foo; // OK: Foo is a runtime binding in this scope
+    return new Foo(); // OK: Foo is a runtime binding in this scope
   }
 };
 
-var bar1: Bar = new Bar;
+var bar1: Bar = new Bar();
 // OK
 var bar2: Bar = Bar.factory();
 // OK
 // NB: Don\'t write expected errors using Foo to avoid error collapse hiding an
 // unexpected failure in the above code.
 var B = class Baz {};
-var b = new Baz;
+var b = new Baz();
 // error: Baz is not a runtime binding in this scope
 var C = class Qux {};
-var c: Qux = new C;
+var c: Qux = new C();
 // error: Qux is not a type in this scope
 // OK: anon classes create no binding, but can be bound manually
 var Anon = class {};
-var anon: Anon = new Anon;
+var anon: Anon = new Anon();
 
 class Alias {}
 var _Alias = class Alias {
   static factory(): Alias {
-    return new Alias;
+    return new Alias();
   }
 };
-var alias1: Alias = new _Alias;
+var alias1: Alias = new _Alias();
 // error: bad pun
 var alias2: Alias = _Alias.factory(); // error: bad pun"
 `;
diff --git a/tests/config_munging_underscores/__snapshots__/jsfmt.spec.js.snap b/tests/config_munging_underscores/__snapshots__/jsfmt.spec.js.snap
index f757e036..d42ede62 100644
--- a/tests/config_munging_underscores/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/config_munging_underscores/__snapshots__/jsfmt.spec.js.snap
@@ -85,7 +85,7 @@ class C {
   _p: string;
 }
 
-module.exports = new C;"
+module.exports = new C();"
 `;
 
 exports[`test commonjs_import.js 1`] = `
diff --git a/tests/constructor_annots/__snapshots__/jsfmt.spec.js.snap b/tests/constructor_annots/__snapshots__/jsfmt.spec.js.snap
index 4a656cb6..87424304 100644
--- a/tests/constructor_annots/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/constructor_annots/__snapshots__/jsfmt.spec.js.snap
@@ -60,16 +60,16 @@ var y2: string = Foo2.y; // error, found boolean instead of string
 var z2: string = new Foo2().m();
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 var Foo = require(\"./constructors\").Foo;
-var x: string = new Foo.x;
+var x: string = new Foo().x;
 // error, found number instead of string
 var y: string = Foo.y;
 // error, found number instead of string
-var z: string = new Foo.m();
+var z: string = new Foo().m();
 
 var Foo2 = require(\"./constructors\").Foo2;
-var x2: string = new Foo2.x;
+var x2: string = new Foo2().x;
 // error, found boolean instead of string
 var y2: string = Foo2.y;
 // error, found boolean instead of string
-var z2: string = new Foo2.m();"
+var z2: string = new Foo2().m();"
 `;
diff --git a/tests/core_tests/__snapshots__/jsfmt.spec.js.snap b/tests/core_tests/__snapshots__/jsfmt.spec.js.snap
index a1e3143e..1d739301 100644
--- a/tests/core_tests/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/core_tests/__snapshots__/jsfmt.spec.js.snap
@@ -49,7 +49,7 @@ let tests = [
 let tests = [
   // constructor
   function() {
-    new Boolean;
+    new Boolean();
     new Boolean(0);
     new Boolean(-0);
     new Boolean(null);
@@ -128,11 +128,11 @@ function* generator(): Iterable<[string, number]> {
 let tests = [
   // good constructors
   function() {
-    let w = new Map;
+    let w = new Map();
     let x = new Map(null);
     let y = new Map([ [ \"foo\", 123 ] ]);
     let z = new Map(generator());
-    let a: Map<string, number> = new Map;
+    let a: Map<string, number> = new Map();
     let b: Map<string, number> = new Map([ [ \"foo\", 123 ] ]);
     let c: Map<string, number> = new Map(generator());
   },
@@ -254,7 +254,7 @@ let ws5 = new WeakSet(numbers()); // error, must be objects
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // @flow
 
-let ws = new WeakSet;
+let ws = new WeakSet();
 let obj: Object = {};
 let dict: { foo: string } = { foo: \"bar\" };
 
diff --git a/tests/covariance/__snapshots__/jsfmt.spec.js.snap b/tests/covariance/__snapshots__/jsfmt.spec.js.snap
index f6994bb1..a3cf7b2c 100644
--- a/tests/covariance/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/covariance/__snapshots__/jsfmt.spec.js.snap
@@ -61,7 +61,7 @@ class NVerbose<E, I: E> {
   }
 }
 
-var nv: NVerbose<number, *> = new NVerbose;
+var nv: NVerbose<number, *> = new NVerbose();
 nv.x = [ 0 ];
 (nv.x[0]: string);
 // error
diff --git a/tests/date/__snapshots__/jsfmt.spec.js.snap b/tests/date/__snapshots__/jsfmt.spec.js.snap
index 8dd5a0f3..5960075e 100644
--- a/tests/date/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/date/__snapshots__/jsfmt.spec.js.snap
@@ -34,7 +34,7 @@ var x: string = d.getTime();
 var y: number = d;
 
 // valid constructors
-new Date;
+new Date();
 new Date(1234567890);
 new Date(\"2015/06/18\");
 new Date(2015, 6);
diff --git a/tests/declaration_files_incremental_haste/__snapshots__/jsfmt.spec.js.snap b/tests/declaration_files_incremental_haste/__snapshots__/jsfmt.spec.js.snap
index d4857862..3e4f0f33 100644
--- a/tests/declaration_files_incremental_haste/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/declaration_files_incremental_haste/__snapshots__/jsfmt.spec.js.snap
@@ -6,7 +6,7 @@ export function foo(): Implementation { return new Implementation; }
 /* @providesModule A */
 class Implementation {}
 export function foo(): Implementation {
-  return new Implementation;
+  return new Implementation();
 }"
 `;
 
@@ -25,7 +25,7 @@ module.exports.fun = (): Implementation => new Implementation;
  */
 
 class Implementation {}
-module.exports.fun = (): Implementation => new Implementation;"
+module.exports.fun = (): Implementation => new Implementation();"
 `;
 
 exports[`test ExplicitProvidesModuleSameName.js 1`] = `
@@ -43,7 +43,7 @@ module.exports.fun = (): Implementation => new Implementation;
  */
 
 class Implementation {}
-module.exports.fun = (): Implementation => new Implementation;"
+module.exports.fun = (): Implementation => new Implementation();"
 `;
 
 exports[`test ImplicitProvidesModule.js 1`] = `
@@ -61,7 +61,7 @@ module.exports.fun = (): Implementation => new Implementation;
  */
 
 class Implementation {}
-module.exports.fun = (): Implementation => new Implementation;"
+module.exports.fun = (): Implementation => new Implementation();"
 `;
 
 exports[`test md5.js 1`] = `
diff --git a/tests/declaration_files_incremental_haste/external/_d3/__snapshots__/jsfmt.spec.js.snap b/tests/declaration_files_incremental_haste/external/_d3/__snapshots__/jsfmt.spec.js.snap
index 3385c24d..ce8fdd85 100644
--- a/tests/declaration_files_incremental_haste/external/_d3/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/declaration_files_incremental_haste/external/_d3/__snapshots__/jsfmt.spec.js.snap
@@ -3,5 +3,5 @@ exports[`test min.js 1`] = `
 module.exports.fun = (): Implementation => new Implementation;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 class Implementation {}
-module.exports.fun = (): Implementation => new Implementation;"
+module.exports.fun = (): Implementation => new Implementation();"
 `;
diff --git a/tests/declaration_files_incremental_node/__snapshots__/jsfmt.spec.js.snap b/tests/declaration_files_incremental_node/__snapshots__/jsfmt.spec.js.snap
index 88c50d5f..f3cbb366 100644
--- a/tests/declaration_files_incremental_node/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/declaration_files_incremental_node/__snapshots__/jsfmt.spec.js.snap
@@ -4,7 +4,7 @@ export function foo(): Implementation { return new Implementation; }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 class Implementation {}
 export function foo(): Implementation {
-  return new Implementation;
+  return new Implementation();
 }"
 `;
 
diff --git a/tests/declare_export/__snapshots__/jsfmt.spec.js.snap b/tests/declare_export/__snapshots__/jsfmt.spec.js.snap
index d3b54776..67666fab 100644
--- a/tests/declare_export/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/declare_export/__snapshots__/jsfmt.spec.js.snap
@@ -908,22 +908,22 @@ import {doesntExist2} from \"CommonJS_Clobbering_Class\";
 import {staticNumber1, baseProp, childProp} from \"CommonJS_Clobbering_Class\";
 // Error
 import CJS_Clobb_Class from \"CommonJS_Clobbering_Class\";
-new CJS_Clobb_Class;
-new CJS_Clobb_Class.doesntExist;
+new CJS_Clobb_Class();
+new CJS_Clobb_Class().doesntExist;
 // Error: Class has no \`doesntExist\` property
 var h1: number = CJS_Clobb_Class.staticNumber2();
 var h2: string = CJS_Clobb_Class.staticNumber2();
 // Error: number ~> string
-var h3: number = new CJS_Clobb_Class.instNumber1();
-var h4: string = new CJS_Clobb_Class.instNumber1();
+var h3: number = new CJS_Clobb_Class().instNumber1();
+var h4: string = new CJS_Clobb_Class().instNumber1();
 // Error: number ~> string
 import * as CJS_Clobb_Class_NS from \"CommonJS_Clobbering_Class\";
-new CJS_Clobb_Class_NS;
+new CJS_Clobb_Class_NS();
 // Error: Namespace object isn\'t constructable
 var i1: number = CJS_Clobb_Class_NS.staticNumber3();
 // Error: Class statics not copied to Namespace object
-var i2: number = new CJS_Clobb_Class_NS.default.instNumber2();
-var i3: string = new CJS_Clobb_Class_NS.default.instNumber2();
+var i2: number = new CJS_Clobb_Class_NS.default().instNumber2();
+var i3: string = new CJS_Clobb_Class_NS.default().instNumber2();
 // Error: number ~> string
 // =================================== //
 // == CommonJS Named Exports -> ES6 == //
@@ -964,8 +964,8 @@ var o1: number = ES6_Def_NamedFunc1();
 var o2: string = ES6_Def_NamedFunc1();
 // Error: number ~> string
 import ES6_Def_NamedClass1 from \"ES6_Default_NamedClass1\";
-var q1: number = new ES6_Def_NamedClass1.givesANum();
-var q2: string = new ES6_Def_NamedClass1.givesANum();
+var q1: number = new ES6_Def_NamedClass1().givesANum();
+var q2: string = new ES6_Def_NamedClass1().givesANum();
 // Error: number ~> string
 ////////////////////////////
 // == ES6 Named -> ES6 == //
@@ -996,8 +996,8 @@ var v1: number = givesANumber();
 var v2: string = givesANumber();
 // Error: number ~> string
 import {NumberGenerator} from \"ES6_Named1\";
-var w1: number = new NumberGenerator.givesANumber();
-var w2: string = new NumberGenerator.givesANumber();
+var w1: number = new NumberGenerator().givesANumber();
+var w2: string = new NumberGenerator().givesANumber();
 // Error: number ~> string
 import {varDeclNumber1, varDeclNumber2} from \"ES6_Named1\";
 var x1: number = varDeclNumber1;
@@ -1032,8 +1032,8 @@ var ae1: number = ES6_Def_NamedFunc2();
 var ae2: string = ES6_Def_NamedFunc2();
 // Error: number ~> string
 var ES6_Def_NamedClass2 = require(\"ES6_Default_NamedClass2\").default;
-var ag1: number = new ES6_Def_NamedClass2.givesANum();
-var ag2: string = new ES6_Def_NamedClass2.givesANum();
+var ag1: number = new ES6_Def_NamedClass2().givesANum();
+var ag2: string = new ES6_Def_NamedClass2().givesANum();
 // Error: number ~> string
 /////////////////////////////////
 // == ES6 Named -> CommonJS == //
@@ -1059,8 +1059,8 @@ var ak1: number = givesANumber2();
 var ak2: string = givesANumber2();
 // Error: number ~> string
 var NumberGenerator2 = require(\"ES6_Named2\").NumberGenerator2;
-var al1: number = new NumberGenerator2.givesANumber();
-var al2: string = new NumberGenerator2.givesANumber();
+var al1: number = new NumberGenerator2().givesANumber();
+var al2: string = new NumberGenerator2().givesANumber();
 // Error: number ~> string
 var varDeclNumber3 = require(\"ES6_Named2\").varDeclNumber3;
 var varDeclNumber4 = require(\"ES6_Named2\").varDeclNumber4;
diff --git a/tests/destructuring/__snapshots__/jsfmt.spec.js.snap b/tests/destructuring/__snapshots__/jsfmt.spec.js.snap
index 8eb7086c..90fef426 100644
--- a/tests/destructuring/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/destructuring/__snapshots__/jsfmt.spec.js.snap
@@ -372,7 +372,7 @@ class Child extends Base {
   childprop2: number;
 }
 
-var { baseprop1, childprop1, ...others } = new Child;
+var { baseprop1, childprop1, ...others } = new Child();
 
 var bp1: number = baseprop1;
 var bp1_err: string = baseprop1;
diff --git a/tests/dictionary/__snapshots__/jsfmt.spec.js.snap b/tests/dictionary/__snapshots__/jsfmt.spec.js.snap
index a800c1ab..97766912 100644
--- a/tests/dictionary/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/dictionary/__snapshots__/jsfmt.spec.js.snap
@@ -411,11 +411,11 @@ function unsound_dict_has_every_key(o: { [k: string]: X }) {
 
 // As with any object type, we can assign subtypes to properties.
 function set_prop_covariant(o: { [k: string]: B }) {
-  o.p = new A;
+  o.p = new A();
   // error, A ~> B
-  o.p = new B;
+  o.p = new B();
   // ok
-  o.p = new C; // ok
+  o.p = new C(); // ok
 }
 
 // This isn\'t specific behavior to dictionaries, but for completeness...
@@ -472,7 +472,7 @@ function unsound_string_conversion_alias_declared_prop(
 function unification_dict_values_invariant(x: Array<{ [k: string]: B }>) {
   let a: Array<{ [k: string]: A }> = x;
   // error
-  a[0].p = new A;
+  a[0].p = new A();
   // in[0].p no longer B
   let b: Array<{ [k: string]: B }> = x;
   // ok
@@ -484,7 +484,7 @@ function unification_dict_values_invariant(x: Array<{ [k: string]: B }>) {
 function subtype_dict_values_invariant(x: { [k: string]: B }) {
   let a: { [k: string]: A } = x;
   // error
-  a.p = new A;
+  a.p = new A();
   // x[0].p no longer B
   let b: { [k: string]: B } = x;
   // ok
@@ -495,30 +495,30 @@ function subtype_dict_values_invariant(x: { [k: string]: B }) {
 
 function subtype_dict_values_fresh_exception() {
   let a: { [k: string]: A } = {
-    a: new A,
+    a: new A(),
     // ok, A == A
-    b: new B,
+    b: new B(),
     // ok, B <: A
     // ok, C <: A
-    c: new C
+    c: new C()
   };
 
   let b: { [k: string]: B } = {
-    a: new A,
+    a: new A(),
     // error, A not <: B
-    b: new B,
+    b: new B(),
     // ok, B == B
     // ok, C <: A
-    c: new C
+    c: new C()
   };
 
   let c: { [k: string]: C } = {
-    a: new A,
+    a: new A(),
     // error, A not <: C
-    b: new B,
+    b: new B(),
     // error, A not <: C
     // ok, C == C
-    c: new C
+    c: new C()
   };
 }
 
@@ -548,7 +548,7 @@ function unification_mix_with_declared_props_invariant_l(
 ) {
   let a: Array<{ [k: string]: B, p: A }> = x;
   // error: A ~> B
-  a[0].p = new A;
+  a[0].p = new A();
   // x[0].p no longer B
   let b: Array<{ [k: string]: B, p: B }> = x;
   // ok
@@ -564,7 +564,7 @@ function unification_mix_with_declared_props_invariant_r(
 ) {
   let a: Array<{ [k: string]: A }> = xa;
   // error
-  a[0].p = new A;
+  a[0].p = new A();
   // xa[0].p no longer B
   let b: Array<{ [k: string]: B }> = xb;
   // ok
@@ -576,7 +576,7 @@ function unification_mix_with_declared_props_invariant_r(
 function subtype_mix_with_declared_props_invariant_l(x: { [k: string]: B }) {
   let a: { [k: string]: B, p: A } = x;
   // error: A ~> B
-  a.p = new A;
+  a.p = new A();
   // x.p no longer B
   let b: { [k: string]: B, p: B } = x;
   // ok
@@ -592,7 +592,7 @@ function subtype_mix_with_declared_props_invariant_r(
 ) {
   let a: { [k: string]: A } = xa;
   // error
-  a.p = new A;
+  a.p = new A();
   // xa.p no longer B
   let b: { [k: string]: B } = xb;
   // ok
@@ -616,7 +616,7 @@ function unification_obj_to_dict(
 function subtype_dict_to_obj(x: { [k: string]: B }) {
   let a: { p: A } = x;
   // error
-  a.p = new A;
+  a.p = new A();
   // x.p no longer B
   let b: { p: B } = x;
   // ok
@@ -628,7 +628,7 @@ function subtype_dict_to_obj(x: { [k: string]: B }) {
 function subtype_obj_to_dict(x: { p: B }) {
   let a: { [k: string]: A } = x;
   // error
-  a.p = new A;
+  a.p = new A();
   // x.p no longer B
   let b: { [k: string]: B } = x;
 
diff --git a/tests/dom/__snapshots__/jsfmt.spec.js.snap b/tests/dom/__snapshots__/jsfmt.spec.js.snap
index 9526397a..1da6f769 100644
--- a/tests/dom/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/dom/__snapshots__/jsfmt.spec.js.snap
@@ -297,14 +297,14 @@ let listener: EventListener = function(event: Event): void {};
 let tests = [
   // attachEvent
   function() {
-    let target = new EventTarget;
+    let target = new EventTarget();
     (target.attachEvent(\"foo\", listener): void);
     // invalid, may be undefined
     (target.attachEvent && target.attachEvent(\"foo\", listener): void); // valid
   },
   // detachEvent
   function() {
-    let target = new EventTarget;
+    let target = new EventTarget();
     (target.detachEvent(\"foo\", listener): void);
     // invalid, may be undefined
     (target.detachEvent && target.detachEvent(\"foo\", listener): void); // valid
@@ -335,7 +335,7 @@ let tests = [
 let tests = [
   // arcTo
   function() {
-    let path = new Path2D;
+    let path = new Path2D();
     (path.arcTo(0, 0, 0, 0, 10): void);
     // valid
     (path.arcTo(0, 0, 0, 0, 10, 20, 5): void);
diff --git a/tests/duplicate_methods/__snapshots__/jsfmt.spec.js.snap b/tests/duplicate_methods/__snapshots__/jsfmt.spec.js.snap
index 81e14103..66511d1d 100644
--- a/tests/duplicate_methods/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/duplicate_methods/__snapshots__/jsfmt.spec.js.snap
@@ -40,7 +40,7 @@ class C1 {
   m() {}
 }
 
-new C1.m();
+new C1().m();
 
 class C2 {
   get m() {
@@ -49,14 +49,14 @@ class C2 {
   m() {}
 }
 
-new C2.m();
+new C2().m();
 
 class C3 {
   set m(x) {}
   m() {}
 }
 
-new C3.m();
+new C3().m();
 
 class C4 {
   get m() {
@@ -65,7 +65,7 @@ class C4 {
   set m(x: number) {}
 }
 
-new C4.m = new C4.m - 42;
+new C4().m = new C4().m - 42;
 
 class C5 {
   m() {}
@@ -75,5 +75,5 @@ class C5 {
   set m(x: number) {}
 }
 
-new C5.m = new C5.m - 42;"
+new C5().m = new C5().m - 42;"
 `;
diff --git a/tests/encaps/__snapshots__/jsfmt.spec.js.snap b/tests/encaps/__snapshots__/jsfmt.spec.js.snap
index 526e1305..459e71ef 100644
--- a/tests/encaps/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/encaps/__snapshots__/jsfmt.spec.js.snap
@@ -17,7 +17,7 @@ var s3 = tag2 \`la la la\`;
 (s3.foo: number); // error: string ~> number
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 class A {}
-var a = new A;
+var a = new A();
 var s1 = \`l\${a.x}r\`;
 // error: no prop x in A
 function tag(strings, ...values) {
diff --git a/tests/es6modules/__snapshots__/jsfmt.spec.js.snap b/tests/es6modules/__snapshots__/jsfmt.spec.js.snap
index 1a040a9c..1a1634e9 100644
--- a/tests/es6modules/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/es6modules/__snapshots__/jsfmt.spec.js.snap
@@ -245,7 +245,7 @@ export default class Foo {
 // Regression test for https://github.com/facebook/flow/issues/511
 //
 // Default-exported class should also be available in local scope
-new Foo;"
+new Foo();"
 `;
 
 exports[`test ES6_Default_NamedClass2.js 1`] = `
@@ -1011,22 +1011,22 @@ import {doesntExist2} from \"CommonJS_Clobbering_Class\";
 import {staticNumber1, baseProp, childProp} from \"CommonJS_Clobbering_Class\";
 // Error
 import CJS_Clobb_Class from \"CommonJS_Clobbering_Class\";
-new CJS_Clobb_Class;
-new CJS_Clobb_Class.doesntExist;
+new CJS_Clobb_Class();
+new CJS_Clobb_Class().doesntExist;
 // Error: Class has no \`doesntExist\` property
 var h1: number = CJS_Clobb_Class.staticNumber2();
 var h2: string = CJS_Clobb_Class.staticNumber2();
 // Error: number ~> string
-var h3: number = new CJS_Clobb_Class.instNumber1();
-var h4: string = new CJS_Clobb_Class.instNumber1();
+var h3: number = new CJS_Clobb_Class().instNumber1();
+var h4: string = new CJS_Clobb_Class().instNumber1();
 // Error: number ~> string
 import * as CJS_Clobb_Class_NS from \"CommonJS_Clobbering_Class\";
-new CJS_Clobb_Class_NS;
+new CJS_Clobb_Class_NS();
 // Error: Namespace object isn\'t constructable
 var i1: number = CJS_Clobb_Class_NS.staticNumber3();
 // Error: Class statics not copied to Namespace object
-var i2: number = new CJS_Clobb_Class_NS.default.instNumber2();
-var i3: string = new CJS_Clobb_Class_NS.default.instNumber2();
+var i2: number = new CJS_Clobb_Class_NS.default().instNumber2();
+var i3: string = new CJS_Clobb_Class_NS.default().instNumber2();
 // Error: number ~> string
 // =================================== //
 // == CommonJS Named Exports -> ES6 == //
@@ -1067,12 +1067,12 @@ var o1: number = ES6_Def_NamedFunc1();
 var o2: string = ES6_Def_NamedFunc1();
 // Error: number ~> string
 import ES6_Def_AnonClass1 from \"ES6_Default_AnonClass1\";
-var p1: number = new ES6_Def_AnonClass1.givesANum();
-var p2: string = new ES6_Def_AnonClass1.givesANum();
+var p1: number = new ES6_Def_AnonClass1().givesANum();
+var p2: string = new ES6_Def_AnonClass1().givesANum();
 // Error: number ~> string
 import ES6_Def_NamedClass1 from \"ES6_Default_NamedClass1\";
-var q1: number = new ES6_Def_NamedClass1.givesANum();
-var q2: string = new ES6_Def_NamedClass1.givesANum();
+var q1: number = new ES6_Def_NamedClass1().givesANum();
+var q2: string = new ES6_Def_NamedClass1().givesANum();
 // Error: number ~> string
 ////////////////////////////
 // == ES6 Named -> ES6 == //
@@ -1103,8 +1103,8 @@ var v1: number = givesANumber();
 var v2: string = givesANumber();
 // Error: number ~> string
 import {NumberGenerator} from \"ES6_Named1\";
-var w1: number = new NumberGenerator.givesANumber();
-var w2: string = new NumberGenerator.givesANumber();
+var w1: number = new NumberGenerator().givesANumber();
+var w2: string = new NumberGenerator().givesANumber();
 // Error: number ~> string
 import {varDeclNumber1, varDeclNumber2} from \"ES6_Named1\";
 var x1: number = varDeclNumber1;
@@ -1147,12 +1147,12 @@ var ae1: number = ES6_Def_NamedFunc2();
 var ae2: string = ES6_Def_NamedFunc2();
 // Error: number ~> string
 var ES6_Def_AnonClass2 = require(\"ES6_Default_AnonClass2\").default;
-var af1: number = new ES6_Def_AnonClass2.givesANum();
-var af2: string = new ES6_Def_AnonClass2.givesANum();
+var af1: number = new ES6_Def_AnonClass2().givesANum();
+var af2: string = new ES6_Def_AnonClass2().givesANum();
 // Error: number ~> string
 var ES6_Def_NamedClass2 = require(\"ES6_Default_NamedClass2\").default;
-var ag1: number = new ES6_Def_NamedClass2.givesANum();
-var ag2: string = new ES6_Def_NamedClass2.givesANum();
+var ag1: number = new ES6_Def_NamedClass2().givesANum();
+var ag2: string = new ES6_Def_NamedClass2().givesANum();
 // Error: number ~> string
 /////////////////////////////////
 // == ES6 Named -> CommonJS == //
@@ -1178,8 +1178,8 @@ var ak1: number = givesANumber2();
 var ak2: string = givesANumber2();
 // Error: number ~> string
 var NumberGenerator2 = require(\"ES6_Named2\").NumberGenerator2;
-var al1: number = new NumberGenerator2.givesANumber();
-var al2: string = new NumberGenerator2.givesANumber();
+var al1: number = new NumberGenerator2().givesANumber();
+var al2: string = new NumberGenerator2().givesANumber();
 // Error: number ~> string
 var varDeclNumber3 = require(\"ES6_Named2\").varDeclNumber3;
 var varDeclNumber4 = require(\"ES6_Named2\").varDeclNumber4;
diff --git a/tests/es_declare_module/__snapshots__/jsfmt.spec.js.snap b/tests/es_declare_module/__snapshots__/jsfmt.spec.js.snap
index 10d8101f..b8fc7736 100644
--- a/tests/es_declare_module/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/es_declare_module/__snapshots__/jsfmt.spec.js.snap
@@ -76,10 +76,10 @@ import {num3} from \"ES\";
 // Error: number ~> string
 import {C} from \"ES\";
 import type {C as CType} from \"ES\";
-(new C: C);
+(new C(): C);
 (42: C);
 // Error: number ~> C
-(new C: CType);
+(new C(): CType);
 (42: CType);
 // Error: number ~> CType
 import {T} from \"ES\";
diff --git a/tests/fetch/__snapshots__/jsfmt.spec.js.snap b/tests/fetch/__snapshots__/jsfmt.spec.js.snap
index 8034ad48..f72dcd8d 100644
--- a/tests/fetch/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/fetch/__snapshots__/jsfmt.spec.js.snap
@@ -88,7 +88,7 @@ const c = new Headers({ \"Content-Type\", \"image/jpeg\" });
 // correct
 const d = new Headers(c);
 // correct
-const e: Headers = new Headers;
+const e: Headers = new Headers();
 // correct
 e.append(\"Content-Type\", \"image/jpeg\");
 // correct
@@ -173,7 +173,7 @@ h.arrayBuffer().then((ab: ArrayBuffer) => ab); // correct
 h.arrayBuffer().then((ab: Buffer) => ab); // incorrect
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 /* @flow */
-const a: Request = new Request;
+const a: Request = new Request();
 // incorrect
 const b: Request = new Request(\"http://example.org\");
 // correct
@@ -276,13 +276,13 @@ h.arrayBuffer().then((ab: ArrayBuffer) => ab); // correct
 h.arrayBuffer().then((ab: Buffer) => ab); // incorrect
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 /* @flow */
-const a: Response = new Response;
+const a: Response = new Response();
 // correct
-const b: Response = new Response(new Blob);
+const b: Response = new Response(new Blob());
 // correct
-const c: Response = new Response(new FormData);
+const c: Response = new Response(new FormData());
 // correct
-const d: Response = new Response(new FormData, { status: 404 });
+const d: Response = new Response(new FormData(), { status: 404 });
 // correct
 const e: Response = new Response(\"responsebody\", { status: \"404\" });
 // incorrect
@@ -358,7 +358,7 @@ const c = new URLSearchParams({ \"key1\", \"value1\" });
 // not correct
 const d = new URLSearchParams(c);
 // correct
-const e: URLSearchParams = new URLSearchParams;
+const e: URLSearchParams = new URLSearchParams();
 // correct
 e.append(\"key1\", \"value1\");
 // correct
diff --git a/tests/generators/__snapshots__/jsfmt.spec.js.snap b/tests/generators/__snapshots__/jsfmt.spec.js.snap
index 43c95d6a..55f74c5e 100644
--- a/tests/generators/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/generators/__snapshots__/jsfmt.spec.js.snap
@@ -226,7 +226,7 @@ class GeneratorExamples {
   }
 }
 
-var examples = new GeneratorExamples;
+var examples = new GeneratorExamples();
 
 for (var x of examples.infer_stmt()) {
   (x: string);
@@ -297,7 +297,7 @@ class GeneratorExamples<X> {
   }
 }
 
-var examples = new GeneratorExamples;
+var examples = new GeneratorExamples();
 
 for (var x of examples.infer_stmt()) {
   (x: string);
diff --git a/tests/generics/__snapshots__/jsfmt.spec.js.snap b/tests/generics/__snapshots__/jsfmt.spec.js.snap
index 61fade52..f36dbc1d 100644
--- a/tests/generics/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/generics/__snapshots__/jsfmt.spec.js.snap
@@ -62,7 +62,7 @@ class D<T> {
   }
 }
 
-var d = new D;
+var d = new D();
 var o = {};
 var b = d.m(true, 0, o);
 var s: string = d.x;
@@ -78,7 +78,7 @@ class E<X> extends C<X> {
   }
 }
 
-var e = new E;
+var e = new E();
 // error: too few arguments to inherited constructor
 var x: string = e.set(0);
 
@@ -91,7 +91,7 @@ class H<Z> extends G<Array<Z>> {
   }
 }
 
-var h1 = new H;
+var h1 = new H();
 h1.foo([ \"...\" ]);
 var h2: F<Array<Array<Array<number>>>> = h1;
 
diff --git a/tests/geolocation/__snapshots__/jsfmt.spec.js.snap b/tests/geolocation/__snapshots__/jsfmt.spec.js.snap
index f9f1420e..b3381792 100644
--- a/tests/geolocation/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/geolocation/__snapshots__/jsfmt.spec.js.snap
@@ -22,7 +22,7 @@ geolocation.clearWatch(id);
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 /* @flow */
 
-var geolocation = new Geolocation;
+var geolocation = new Geolocation();
 var id = geolocation.watchPosition(
   position => {
     var coords: Coordinates = position.coords;
diff --git a/tests/getters_and_setters_enabled/__snapshots__/jsfmt.spec.js.snap b/tests/getters_and_setters_enabled/__snapshots__/jsfmt.spec.js.snap
index 80dd57a2..941d350d 100644
--- a/tests/getters_and_setters_enabled/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/getters_and_setters_enabled/__snapshots__/jsfmt.spec.js.snap
@@ -107,7 +107,7 @@ class Foo {
   set propOverriddenWithSetter(x: string) {}
 }
 
-var foo = new Foo;
+var foo = new Foo();
 
 // Test getting properties with getters
 var testGetterNoError1: number = foo.goodGetterNoAnnotation;
@@ -234,12 +234,12 @@ var obj = {
     return 4;
   },
   get exampleOfOrderOfGetterAndSetter(): A {
-    return new A;
+    return new A();
   },
   set exampleOfOrderOfGetterAndSetter(x: B) {},
   set exampleOfOrderOfGetterAndSetterReordered(x: B) {},
   get exampleOfOrderOfGetterAndSetterReordered(): A {
-    return new A;
+    return new A();
   }
 };
 
@@ -264,7 +264,7 @@ var testSubtypingGetterAndSetter: number = obj.propWithSubtypingGetterAndSetter;
 // When building this feature, it was tempting to flow the setter into the
 // getter and then use either the getter or setter as the type of the property.
 // This example shows the danger of using the getter\'s type
-obj.exampleOfOrderOfGetterAndSetter = new C;
+obj.exampleOfOrderOfGetterAndSetter = new C();
 // Error C ~> B
 // And this example shows the danger of using the setter\'s type.
 var testExampleOrOrderOfGetterAndSetterReordered: number = obj.exampleOfOrderOfGetterAndSetterReordered; // Error A ~> B"
diff --git a/tests/immutable_methods/__snapshots__/jsfmt.spec.js.snap b/tests/immutable_methods/__snapshots__/jsfmt.spec.js.snap
index 9dbbe1d5..c1b296bb 100644
--- a/tests/immutable_methods/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/immutable_methods/__snapshots__/jsfmt.spec.js.snap
@@ -20,8 +20,8 @@ class B extends A {
   }
 }
 class C extends A {}
-var a: A = new B;
+var a: A = new B();
 a.foo = function(): C {
-  return new C;
+  return new C();
 };"
 `;
diff --git a/tests/import_type/__snapshots__/jsfmt.spec.js.snap b/tests/import_type/__snapshots__/jsfmt.spec.js.snap
index ad22ccda..8b187734 100644
--- a/tests/import_type/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/import_type/__snapshots__/jsfmt.spec.js.snap
@@ -21,7 +21,7 @@ class ClassFoo3 {
     return 42;
   }
   static givesAFoo3(): ClassFoo3 {
-    return new ClassFoo3;
+    return new ClassFoo3();
   }
 }
 
@@ -65,17 +65,17 @@ class ClassFoo4 {
 class ClassFoo5 {}
 
 function givesAFoo4(): ClassFoo4 {
-  return new ClassFoo4;
+  return new ClassFoo4();
 }
 
 function givesAFoo5(): ClassFoo5 {
-  return new ClassFoo5;
+  return new ClassFoo5();
 }
 
 exports.ClassFoo4 = ClassFoo4;
 exports.ClassFoo5 = ClassFoo5;
-exports.foo4Inst = new ClassFoo4;
-exports.foo5Inst = new ClassFoo5;"
+exports.foo4Inst = new ClassFoo4();
+exports.foo5Inst = new ClassFoo5();"
 `;
 
 exports[`test ExportDefault_Class.js 1`] = `
@@ -101,7 +101,7 @@ class ClassFoo1 {
 }
 
 export default ClassFoo1
-export var foo1Inst = new ClassFoo1;"
+export var foo1Inst = new ClassFoo1();"
 `;
 
 exports[`test ExportNamed_Alias.js 1`] = `
@@ -156,7 +156,7 @@ class ClassFoo2 {
 }
 
 export {ClassFoo2}
-export var foo2Inst = new ClassFoo2;"
+export var foo2Inst = new ClassFoo2();"
 `;
 
 exports[`test ExportsANumber.js 1`] = `
@@ -267,7 +267,7 @@ import {foo1Inst} from \"./ExportDefault_Class\";
 var a1: ClassFoo1 = foo1Inst;
 var a2: number = foo1Inst;
 // Error: ClassFoo1 ~> number
-new ClassFoo1;
+new ClassFoo1();
 // Error: ClassFoo1 is not a value-identifier
 ///////////////////////////////////////////////
 // == Importing Class Type (Named Export) == //
@@ -278,15 +278,15 @@ import {foo2Inst} from \"./ExportNamed_Class\";
 var b1: ClassFoo2 = foo2Inst;
 var b2: number = foo2Inst;
 // Error: ClassFoo2 ~> number
-new ClassFoo2;
+new ClassFoo2();
 // Error: ClassFoo2 is not a value-identifier
 /////////////////////////////////////////////////////
 // == Importing Class Type (CJS Default Export) == //
 /////////////////////////////////////////////////////
 import type ClassFoo3T from \"./ExportCJSDefault_Class\";
 import ClassFoo3 from \"./ExportCJSDefault_Class\";
-var c1: ClassFoo3T = new ClassFoo3;
-new ClassFoo3T;
+var c1: ClassFoo3T = new ClassFoo3();
+new ClassFoo3T();
 // Error: ClassFoo3 is not a value-identifier
 ///////////////////////////////////////////////////
 // == Importing Class Type (CJS Named Export) == //
@@ -297,7 +297,7 @@ import {foo4Inst, foo5Inst} from \"./ExportCJSNamed_Class\";
 var d1: ClassFoo4 = foo4Inst;
 var d2: number = foo4Inst;
 // Error: ClassFoo4 ~> number
-new ClassFoo4;
+new ClassFoo4();
 // Error: ClassFoo4 is not a value-identifier
 // TODO: this errors correctly, but the message is just \'can\'t resolve name\'
 var d3: typeof ClassFoo5 = foo5Inst;
diff --git a/tests/import_typeof/__snapshots__/jsfmt.spec.js.snap b/tests/import_typeof/__snapshots__/jsfmt.spec.js.snap
index 0f819dbc..a4f83afc 100644
--- a/tests/import_typeof/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/import_typeof/__snapshots__/jsfmt.spec.js.snap
@@ -21,7 +21,7 @@ class ClassFoo3 {
     return 42;
   }
   static givesAFoo3(): ClassFoo3 {
-    return new ClassFoo3;
+    return new ClassFoo3();
   }
 }
 
@@ -292,9 +292,9 @@ import typeof ClassFoo1T from \"./ExportDefault_Class\";
 import ClassFoo1 from \"./ExportDefault_Class\";
 
 var a1: ClassFoo1T = ClassFoo1;
-var a2: ClassFoo1T = new ClassFoo1;
+var a2: ClassFoo1T = new ClassFoo1();
 // Error: ClassFoo1 (inst) ~> ClassFoo1 (class)
-new ClassFoo1T;
+new ClassFoo1T();
 // Error: ClassFoo1T is not bound to a value
 /////////////////////////////////////////////////
 // == Importing Class Typeof (Named Export) == //
@@ -303,9 +303,9 @@ import typeof {ClassFoo2 as ClassFoo2T} from \"./ExportNamed_Class\";
 import {ClassFoo2} from \"./ExportNamed_Class\";
 
 var b1: ClassFoo2T = ClassFoo2;
-var b2: ClassFoo2T = new ClassFoo2;
+var b2: ClassFoo2T = new ClassFoo2();
 // Error: ClassFoo2 (inst) ~> ClassFoo2 (class)
-new ClassFoo2T;
+new ClassFoo2T();
 // Error: ClassFoo2T is not bound to a value
 ///////////////////////////////////////////////////////
 // == Importing Class Typeof (CJS Default Export) == //
@@ -314,7 +314,7 @@ import typeof ClassFoo3T from \"./ExportCJSDefault_Class\";
 import ClassFoo3 from \"./ExportCJSDefault_Class\";
 
 var c1: ClassFoo3T = ClassFoo3;
-var c2: ClassFoo3T = new ClassFoo3;
+var c2: ClassFoo3T = new ClassFoo3();
 // Error: ClassFoo3 (inst) ~> ClassFoo3 (class)
 /////////////////////////////////////////////////////
 // == Importing Class Typeof (CJS Named Export) == //
@@ -323,7 +323,7 @@ import typeof {ClassFoo4 as ClassFoo4T} from \"./ExportCJSNamed_Class\";
 import {ClassFoo4} from \"./ExportCJSNamed_Class\";
 
 var d1: ClassFoo4T = ClassFoo4;
-var d2: ClassFoo4T = new ClassFoo4;
+var d2: ClassFoo4T = new ClassFoo4();
 // Error: ClassFoo4 (inst) ~> ClassFoo4 (class)
 //////////////////////////////////////////////
 // == Import Typeof Alias (Named Export) == //
diff --git a/tests/instanceof/__snapshots__/jsfmt.spec.js.snap b/tests/instanceof/__snapshots__/jsfmt.spec.js.snap
index b75a85aa..742ebf3f 100644
--- a/tests/instanceof/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/instanceof/__snapshots__/jsfmt.spec.js.snap
@@ -99,7 +99,7 @@ class X2 {
 }
 
 function x(b) {
-  return b ? new X1 : new X2;
+  return b ? new X1() : new X2();
 }
 
 function consumer1(b) {
@@ -126,7 +126,7 @@ class Y2 {
 }
 
 function y(b) {
-  return b ? new Y1 : new Y2;
+  return b ? new Y1() : new Y2();
 }
 
 function consumer3(b) {
@@ -153,7 +153,7 @@ class Z2 {
 }
 
 function z(b) {
-  return b ? new Z1 : new Z2;
+  return b ? new Z1() : new Z2();
 }
 
 function consumer5(b) {
diff --git a/tests/interface/__snapshots__/jsfmt.spec.js.snap b/tests/interface/__snapshots__/jsfmt.spec.js.snap
index 2e778c66..aa2b5959 100644
--- a/tests/interface/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/interface/__snapshots__/jsfmt.spec.js.snap
@@ -44,11 +44,11 @@ function testInterfaceName(o: I) {
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 declare class C { x: number }
 
-var x: string = new C.x;
+var x: string = new C().x;
 
 interface I  { x: number }
 
-var i = new I;
+var i = new I();
 // error
 function testInterfaceName(o: I) {
   (o.name: string);
@@ -177,5 +177,5 @@ interface I  { foo(x: number): void }
 // error, property \`foo\` not found function
 declare class C { bar(i: I): void, bar(f: (x: number) => void): void }
 
-new C.bar((x: string) => {}); // error, number ~/~> string"
+new C().bar((x: string) => {}); // error, number ~/~> string"
 `;
diff --git a/tests/iterable/__snapshots__/jsfmt.spec.js.snap b/tests/iterable/__snapshots__/jsfmt.spec.js.snap
index 1178ef14..9f92f78b 100644
--- a/tests/iterable/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/iterable/__snapshots__/jsfmt.spec.js.snap
@@ -93,7 +93,7 @@ function foo(strs: Iterable<string>): void {
   }
 }
 
-var m: Map<string, number> = new Map;
+var m: Map<string, number> = new Map();
 
 foo(m.keys());"
 `;
diff --git a/tests/last_duplicate_property_wins/__snapshots__/jsfmt.spec.js.snap b/tests/last_duplicate_property_wins/__snapshots__/jsfmt.spec.js.snap
index 1982e849..6af6c4d8 100644
--- a/tests/last_duplicate_property_wins/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/last_duplicate_property_wins/__snapshots__/jsfmt.spec.js.snap
@@ -68,13 +68,13 @@ class C {
 }
 
 // check
-(new C.foo(): boolean);
+(new C().foo(): boolean);
 // last wins
-(new C.x: boolean);
+(new C().x: boolean);
 // last wins
-(new C.bar: boolean);
+(new C().bar: boolean);
 // last wins
-(new C.qux: boolean);
+(new C().qux: boolean);
 // weird outlier where last doesn\'t win in classes
 // Objects
 const o = {
diff --git a/tests/lib/__snapshots__/jsfmt.spec.js.snap b/tests/lib/__snapshots__/jsfmt.spec.js.snap
index f6d0347b..dd2f03b3 100644
--- a/tests/lib/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/lib/__snapshots__/jsfmt.spec.js.snap
@@ -13,10 +13,10 @@ if (undefined) {
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 var x: string = NaN;
 var y: string = Number.MAX_VALUE;
-var z: number = new TypeError.name;
+var z: number = new TypeError().name;
 var w: string = parseInt(\"...\");
 
-var a = new Map;
+var a = new Map();
 a.delete(\"foobar\");
 
 var b = undefined;
diff --git a/tests/method_properties/__snapshots__/jsfmt.spec.js.snap b/tests/method_properties/__snapshots__/jsfmt.spec.js.snap
index 28edeb1c..3ed323de 100644
--- a/tests/method_properties/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/method_properties/__snapshots__/jsfmt.spec.js.snap
@@ -43,11 +43,11 @@ class C {
   }
 }
 C.x;
-new C.foo.x;
+new C().foo.x;
 C.bar.x;
 
 import {Foo} from \"./exports_optional_prop\";
-const foo = new Foo;
+const foo = new Foo();
 (foo.bar(): string);
 // error, could be undefined
 function f(x) {
diff --git a/tests/misc/__snapshots__/jsfmt.spec.js.snap b/tests/misc/__snapshots__/jsfmt.spec.js.snap
index 8c5a40ed..46cc3a7e 100644
--- a/tests/misc/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/misc/__snapshots__/jsfmt.spec.js.snap
@@ -86,7 +86,7 @@ var B = require(\"B\");
 var f = require(\"A\").fn;
 
 function C() {
-  var o = new B;
+  var o = new B();
   f(o.b);
   f(o.s);
   o.fn();
diff --git a/tests/more_annot/__snapshots__/jsfmt.spec.js.snap b/tests/more_annot/__snapshots__/jsfmt.spec.js.snap
index 80f6ba5f..2ab283b2 100644
--- a/tests/more_annot/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/more_annot/__snapshots__/jsfmt.spec.js.snap
@@ -42,9 +42,9 @@ function Foo() {
 }
 Foo.prototype.m = function() {};
 
-var o1: { x: number, m(): void } = new Foo;
+var o1: { x: number, m(): void } = new Foo();
 
-var o2: Foo = new Foo;"
+var o2: Foo = new Foo();"
 `;
 
 exports[`test super.js 1`] = `
@@ -58,5 +58,5 @@ class C {
 }
 class D extends C {}
 
-var d: { +m: () => void } = new D;"
+var d: { +m: () => void } = new D();"
 `;
diff --git a/tests/more_classes/__snapshots__/jsfmt.spec.js.snap b/tests/more_classes/__snapshots__/jsfmt.spec.js.snap
index 3536c1a6..53e445a2 100644
--- a/tests/more_classes/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/more_classes/__snapshots__/jsfmt.spec.js.snap
@@ -33,7 +33,7 @@ class Bar {
   }
 
   bar(z: string, u: string): string {
-    new Qux.w = \"?\";
+    new Qux().w = \"?\";
     return z;
   }
 }
diff --git a/tests/more_path/__snapshots__/jsfmt.spec.js.snap b/tests/more_path/__snapshots__/jsfmt.spec.js.snap
index 30cd4af4..efffb41c 100644
--- a/tests/more_path/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/more_path/__snapshots__/jsfmt.spec.js.snap
@@ -72,7 +72,7 @@ f(x);
 
 class A {}
 function h() {
-  return 42 || new A;
+  return 42 || new A();
 }
 
 var y = h();
@@ -90,7 +90,7 @@ class C {
 
 function foo() {
   var c = \"...\";
-  c = new C;
+  c = new C();
   if (bar()) {
     c.qux();
   }
diff --git a/tests/name_prop/__snapshots__/jsfmt.spec.js.snap b/tests/name_prop/__snapshots__/jsfmt.spec.js.snap
index d9e14e2f..98fca7d3 100644
--- a/tests/name_prop/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/name_prop/__snapshots__/jsfmt.spec.js.snap
@@ -17,7 +17,7 @@ var test1 = A.bar;
 var test2: string = A.name;
 var test3: number = A.name;
 // Error string ~> number
-var a = new A;
+var a = new A();
 var test4 = a.constructor.bar;
 // Error bar doesn\'t exist
 var test5: string = a.constructor.name;
diff --git a/tests/node_tests/stream/__snapshots__/jsfmt.spec.js.snap b/tests/node_tests/stream/__snapshots__/jsfmt.spec.js.snap
index ec974995..e3dc0506 100644
--- a/tests/node_tests/stream/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/node_tests/stream/__snapshots__/jsfmt.spec.js.snap
@@ -61,8 +61,8 @@ class MyWriteStream extends stream.Writable {}
 class MyDuplex extends stream.Duplex {}
 class MyTransform extends stream.Duplex {}
 
-new MyReadStream
-  .pipe(new MyDuplex)
-  .pipe(new MyTransform)
-  .pipe(new MyWriteStream);"
+new MyReadStream()
+  .pipe(new MyDuplex())
+  .pipe(new MyTransform())
+  .pipe(new MyWriteStream());"
 `;
diff --git a/tests/object_api/__snapshots__/jsfmt.spec.js.snap b/tests/object_api/__snapshots__/jsfmt.spec.js.snap
index 1c401dc4..aeffb1dd 100644
--- a/tests/object_api/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/object_api/__snapshots__/jsfmt.spec.js.snap
@@ -96,7 +96,7 @@ class C {
 (Object.create(C.prototype): C);
 
 // OK, \`instanceof C\` would be true
-(Object.create(new C): C);
+(Object.create(new C()): C);
 
 // error, object literals don\'t structurally match instances
 ({ foo: \"foo\" }: C);
@@ -127,7 +127,7 @@ class Bar extends Foo {}
 
 let tests = [
   function() {
-    const x = new Bar;
+    const x = new Bar();
     (Object.getPrototypeOf(x): Foo);
   }
 ];"
@@ -191,14 +191,14 @@ class Foo {
   foo() {}
 }
 // constructor and foo not enumerable
-(Object.keys(new Foo): Array<\"error\">);
+(Object.keys(new Foo()): Array<\"error\">);
 // error: prop ~> error
 class Bar extends Foo {
   bar_prop: string;
   bar() {}
 }
 // only own enumerable props
-(Object.keys(new Bar): Array<\"error\">); // error: bar_prop ~> error"
+(Object.keys(new Bar()): Array<\"error\">); // error: bar_prop ~> error"
 `;
 
 exports[`test object_missing.js 1`] = `
@@ -403,8 +403,8 @@ var c = {
   }
 };
 var d: { [key: string]: string } = { foo: \"bar\" };
-var x = new Date;
-var y = new Foo;
+var x = new Date();
+var y = new Foo();
 
 //
 // toString
diff --git a/tests/optional/__snapshots__/jsfmt.spec.js.snap b/tests/optional/__snapshots__/jsfmt.spec.js.snap
index 4fc0e81a..354b30be 100644
--- a/tests/optional/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/optional/__snapshots__/jsfmt.spec.js.snap
@@ -273,7 +273,7 @@ var i:I<number> = new I();
 var j:I<number> = i.map(id => id);
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 declare class I<V> { map<M>(mapper: (value?: V) => M): I<M> }
-var i: I<number> = new I;
+var i: I<number> = new I();
 var j: I<number> = i.map(id => id);"
 `;
 
diff --git a/tests/overload/__snapshots__/jsfmt.spec.js.snap b/tests/overload/__snapshots__/jsfmt.spec.js.snap
index 3a350ea2..5274df88 100644
--- a/tests/overload/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/overload/__snapshots__/jsfmt.spec.js.snap
@@ -69,7 +69,7 @@ declare class C {
   bar(x: { a: string }): string
 }
 
-var a = new C;
+var a = new C();
 
 a.foo(0);
 // ok
@@ -113,8 +113,8 @@ exports[`test test.js 1`] = `
 }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 function foo() {
-  var output = new FakeUint8Array;
-  output.set(new FakeUint8Array, 0); // matches one of the overloads of set
+  var output = new FakeUint8Array();
+  output.set(new FakeUint8Array(), 0); // matches one of the overloads of set
 }"
 `;
 
@@ -128,7 +128,7 @@ var foo = new Foo;
 (foo.bar(\'hmmm\'): number); // error
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 declare class Foo { bar(x: \"hmm\"): number, bar(x: string): string }
-var foo = new Foo;
+var foo = new Foo();
 (foo.bar(\"hmm\"): number);
 // OK
 (foo.bar(\"hmmm\"): number); // error"
diff --git a/tests/plsummit/__snapshots__/jsfmt.spec.js.snap b/tests/plsummit/__snapshots__/jsfmt.spec.js.snap
index 826c2973..0d238e61 100644
--- a/tests/plsummit/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/plsummit/__snapshots__/jsfmt.spec.js.snap
@@ -104,7 +104,7 @@ C.prototype.foo = function() {
   return this.x;
 };
 
-var c = new C;
+var c = new C();
 var x: string = c.foo();
 
 function foo() {
diff --git a/tests/poly/__snapshots__/jsfmt.spec.js.snap b/tests/poly/__snapshots__/jsfmt.spec.js.snap
index 851f0580..7e8e283f 100644
--- a/tests/poly/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/poly/__snapshots__/jsfmt.spec.js.snap
@@ -12,18 +12,18 @@ function bar(): A<*> { // error, * can\'t be {} and {x: string} at the same time
 }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 class A<X> {}
-new A;
+new A();
 // OK, implicitly inferred type args
 class B extends A {}
 // OK, same as above
 function foo(b): A<any> {
   // ok but unsafe, caller may assume any type arg
-  return b ? (new A: A<number>) : (new A: A<string>);
+  return b ? (new A(): A<number>) : (new A(): A<string>);
 }
 
 function bar(): A<*> {
   // error, * can\'t be {} and {x: string} at the same time
-  return (new A: A<{}>) || (new A: A<{ x: string }>);
+  return (new A(): A<{}>) || (new A(): A<{ x: string }>);
 }"
 `;
 
@@ -63,13 +63,13 @@ class C<T: Middle> {
 
 // T is implicitly (bounded by) Middle in constructor call if not provided.
 // Explicit type arg is required in annotation - here a wildcard captures it.
-var a: C<*> = new C;
+var a: C<*> = new C();
 
-a.meth(new Middle);
-a.meth(new Child);
+a.meth(new Middle());
+a.meth(new Child());
 a.meth(42);
 // Error: number ~> Middle
-a.meth(new Base); // Error: Base ~> Middle"
+a.meth(new Base()); // Error: Base ~> Middle"
 `;
 
 exports[`test issue-1029.js 1`] = `
diff --git a/tests/poly_class_export/__snapshots__/jsfmt.spec.js.snap b/tests/poly_class_export/__snapshots__/jsfmt.spec.js.snap
index 8dae54a1..b906f798 100644
--- a/tests/poly_class_export/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/poly_class_export/__snapshots__/jsfmt.spec.js.snap
@@ -39,7 +39,7 @@ class B extends A<string> {
   }
 }
 
-module.exports = new B;"
+module.exports = new B();"
 `;
 
 exports[`test C.js 1`] = `
diff --git a/tests/react/__snapshots__/jsfmt.spec.js.snap b/tests/react/__snapshots__/jsfmt.spec.js.snap
index 8f64d0d1..b491f649 100644
--- a/tests/react/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/react/__snapshots__/jsfmt.spec.js.snap
@@ -110,8 +110,8 @@ var b: number = new react.Component(); // Error: ReactComponent ~> number
 import react from \"react\";
 import {Component} from \"react\";
 
-var a: Component<*, *, *> = new react.Component;
-var b: number = new react.Component; // Error: ReactComponent ~> number"
+var a: Component<*, *, *> = new react.Component();
+var b: number = new react.Component(); // Error: ReactComponent ~> number"
 `;
 
 exports[`test jsx_spread.js 1`] = `
diff --git a/tests/rec/__snapshots__/jsfmt.spec.js.snap b/tests/rec/__snapshots__/jsfmt.spec.js.snap
index ce37121f..b72efb5a 100644
--- a/tests/rec/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/rec/__snapshots__/jsfmt.spec.js.snap
@@ -93,7 +93,7 @@ class P<X> {
 // this is like Promise
 type Pstar<X> = X | Pstar<P<X>>;
 // this is like Promise*
-var p: P<number> = new P;
+var p: P<number> = new P();
 (p.x: string);
 // error
 var pstar: Pstar<number> = 0;
@@ -105,7 +105,7 @@ pstar = p;
 // OK
 (pstar.x: string);
 // error
-pstar = (new P: P<P<number>>);
+pstar = (new P(): P<P<number>>);
 // OK
 (pstar.x: string); // error"
 `;
@@ -156,7 +156,7 @@ function bar() {
 class A<X> {
   x: A<A<X>>;
 }
-var a_ = new A;
+var a_ = new A();
 function foo0() {
   a_ = a_.x; // terminate despite expanding types
 }
@@ -172,7 +172,7 @@ function foo1(b: S<*>) {
 class D<X> {}
 class B<X> extends D<X> {}
 class C<X> extends B<X> {}
-((new C: C<number>): D<string>); // error: number ~/~ string"
+((new C(): C<number>): D<string>); // error: number ~/~ string"
 `;
 
 exports[`test test3.js 1`] = `
diff --git a/tests/recheck/__snapshots__/jsfmt.spec.js.snap b/tests/recheck/__snapshots__/jsfmt.spec.js.snap
index 62182935..1bec7bc0 100644
--- a/tests/recheck/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/recheck/__snapshots__/jsfmt.spec.js.snap
@@ -113,7 +113,7 @@ import { C, D } from \"./b2\";
 
 import {C, D} from \"./b2\";
 
-(new D: C);"
+(new D(): C);"
 `;
 
 exports[`test c1.js 1`] = `
@@ -169,7 +169,7 @@ export var x = new A;
 
 export class A {}
 export class B {}
-export var x = new A;"
+export var x = new A();"
 `;
 
 exports[`test d2.js 1`] = `
@@ -304,7 +304,7 @@ import { D } from \'./g2\';
 import {C} from \"./g1\";
 import {D} from \"./g2\";
 
-(new D: C);"
+(new D(): C);"
 `;
 
 exports[`test h1.js 1`] = `
diff --git a/tests/recheck/tmp1d/__snapshots__/jsfmt.spec.js.snap b/tests/recheck/tmp1d/__snapshots__/jsfmt.spec.js.snap
index 882bb60a..d54f91b8 100644
--- a/tests/recheck/tmp1d/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/recheck/tmp1d/__snapshots__/jsfmt.spec.js.snap
@@ -9,5 +9,5 @@ export var x = new B;
 
 export class A {}
 export class B {}
-export var x = new B;"
+export var x = new B();"
 `;
diff --git a/tests/refinements/__snapshots__/jsfmt.spec.js.snap b/tests/refinements/__snapshots__/jsfmt.spec.js.snap
index b30eb89e..7962c57c 100644
--- a/tests/refinements/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/refinements/__snapshots__/jsfmt.spec.js.snap
@@ -414,7 +414,7 @@ function foo1(x: ?Foo): string {
 }
 
 function foo2(x: ?Class<Foo>): string {
-  return x && new x.foo || \"\";
+  return x && new x().foo || \"\";
 }"
 `;
 
diff --git a/tests/return_new/__snapshots__/jsfmt.spec.js.snap b/tests/return_new/__snapshots__/jsfmt.spec.js.snap
index ff481512..34bdf3e8 100644
--- a/tests/return_new/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/return_new/__snapshots__/jsfmt.spec.js.snap
@@ -15,21 +15,21 @@ var a: A = new B(); // OK (returns new A)
 function Foo() {
   return {};
 }
-var foo: number = new Foo;
+var foo: number = new Foo();
 // error (returns object literal above)
 function Bar() {
   return 0;
 }
-var bar: number = new Bar;
+var bar: number = new Bar();
 // error (returns new object)
 function Qux() {}
-var qux: number = new Qux;
+var qux: number = new Qux();
 // error (returns new object)
 class A {}
 function B() {
-  return new A;
+  return new A();
 }
-var a: A = new B; // OK (returns new A)"
+var a: A = new B(); // OK (returns new A)"
 `;
 
 exports[`test test2.js 1`] = `
@@ -51,10 +51,10 @@ declare class D {
   y: any
 }
 
-var d = new D;
+var d = new D();
 d.x = \"\";
 // error, string ~/~ number (but property x is found)
-(new D: D);
+(new D(): D);
 // error, new D is an object, D not in proto chain
 module.exports = D;"
 `;
diff --git a/tests/sealed/__snapshots__/jsfmt.spec.js.snap b/tests/sealed/__snapshots__/jsfmt.spec.js.snap
index 2ab3325f..e82791a9 100644
--- a/tests/sealed/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/sealed/__snapshots__/jsfmt.spec.js.snap
@@ -41,7 +41,7 @@ var export_o: { x:any; } = o; // awkward type cast
 module.exports = export_o;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 function Foo() {}
-var o = new Foo;
+var o = new Foo();
 var x: number = o.x;
 
 Foo.prototype.m = function() {
diff --git a/tests/statics/__snapshots__/jsfmt.spec.js.snap b/tests/statics/__snapshots__/jsfmt.spec.js.snap
index dd3369db..f566f8e1 100644
--- a/tests/statics/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/statics/__snapshots__/jsfmt.spec.js.snap
@@ -38,5 +38,5 @@ C.g = function(x) {
   return x;
 };
 
-var x: string = new C.f();"
+var x: string = new C().f();"
 `;
diff --git a/tests/structural_subtyping/__snapshots__/jsfmt.spec.js.snap b/tests/structural_subtyping/__snapshots__/jsfmt.spec.js.snap
index 9236ea09..217adf85 100644
--- a/tests/structural_subtyping/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/structural_subtyping/__snapshots__/jsfmt.spec.js.snap
@@ -64,10 +64,10 @@ interface IHasXNumber  { x: number }
 
 interface IHasYString  { y: string }
 
-var testInstance1: IHasXString = new ClassWithXString;
-var testInstance2: IHasXNumber = new ClassWithXString;
+var testInstance1: IHasXString = new ClassWithXString();
+var testInstance2: IHasXNumber = new ClassWithXString();
 // Error wrong type
-var testInstance3: IHasYString = new ClassWithXString; // Error missing prop"
+var testInstance3: IHasYString = new ClassWithXString(); // Error missing prop"
 `;
 
 exports[`test obj.js 1`] = `
diff --git a/tests/super/__snapshots__/jsfmt.spec.js.snap b/tests/super/__snapshots__/jsfmt.spec.js.snap
index 1020f9fc..0b0a5fbe 100644
--- a/tests/super/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/super/__snapshots__/jsfmt.spec.js.snap
@@ -286,8 +286,8 @@ class L extends L_ {
     return x;
   }
 }
-(new L_: L_);
-(new L: L);
+(new L_(): L_);
+(new L(): L);
 
 // similarly, the converse is true: if the parent\'s constructor returns an
 // object, then the child does too.
@@ -301,8 +301,8 @@ class M extends M_ {
     return super();
   }
 }
-(new M_: { foo: string });
-(new M: { foo: string });
+(new M_(): { foo: string });
+(new M(): { foo: string });
 
 // however! super() calls the parent constructor with the subclass as its \`this\`
 // value (essentially \`super.constructor.call(this)\`).
@@ -317,8 +317,8 @@ class N extends N_ {
     return super();
   }
 }
-(new N_: N_);
-(new N: N);"
+(new N_(): N_);
+(new N(): N);"
 `;
 
 exports[`test import.js 1`] = `
diff --git a/tests/this/__snapshots__/jsfmt.spec.js.snap b/tests/this/__snapshots__/jsfmt.spec.js.snap
index 497c00fe..a2320e3f 100644
--- a/tests/this/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/this/__snapshots__/jsfmt.spec.js.snap
@@ -71,17 +71,17 @@ F.prototype.m = function() {
 
 function foo(p: string) {}
 
-var o1 = new F;
+var o1 = new F();
 // sets o1.x to 0
 o1.x = \"\";
 foo(o1.x);
 // ok by definite assignment
-var o2 = new F;
+var o2 = new F();
 o1.y = 0;
 o2.y = \"\";
 foo(o2.y);
 // setting o1.y to 0 has no effect on o2.y
-var o3 = new F;
+var o3 = new F();
 o3.m();
 // sets o3.y to 0
 o3.y = \"\";
@@ -175,14 +175,14 @@ class C {
     return this;
   } // return type is C
 }
-var c = new C;
+var c = new C();
 var f = c.foo();
 var i = f();
 // OK
 (i: C);
 // OK
 class D extends C {}
-var d = new D;
+var d = new D();
 var g = d.foo();
 var j = g();
 // OK
diff --git a/tests/this_type/__snapshots__/jsfmt.spec.js.snap b/tests/this_type/__snapshots__/jsfmt.spec.js.snap
index 29930c69..e1049183 100644
--- a/tests/this_type/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/this_type/__snapshots__/jsfmt.spec.js.snap
@@ -83,8 +83,8 @@ class C {
 
 class D extends C {}
 
-var d = new D;
-(d: C).next = new C;
+var d = new D();
+(d: C).next = new C();
 (d.next: D);
 // sneaky
 class A {
@@ -114,7 +114,7 @@ class Invariant {
 class Misc {
   // Set<X> has invariant X
   out_set(): Set<this> {
-    return new Set.add(this);
+    return new Set().add(this);
   }
   in_set(_: Set<this>) {}
   inout_set: Set<this>;
@@ -198,7 +198,7 @@ class ImplicitNumber extends Implicit {
   arg: number;
 }
 
-(new ImplicitNumber.val: string); // error: number ~> string"
+(new ImplicitNumber().val: string); // error: number ~> string"
 `;
 
 exports[`test import.js 1`] = `
@@ -233,27 +233,27 @@ import {A3} from \"./export\";
 
 class B1 extends A1 {
   foo(): B1 {
-    return new B1;
+    return new B1();
   } // error
 }
 
-(new B1.bar(): B1);
+(new B1().bar(): B1);
 // OK
 class B3<X> extends A3<X> {
   foo(): B3<X> {
-    return new B3;
+    return new B3();
   } // error
 }
 
-(new B3.bar(): B3<*>);
+(new B3().bar(): B3<*>);
 // OK
-(new B3.qux(0): string);
+(new B3().qux(0): string);
 // error
-(new B3.bar(): A2<*>);
+(new B3().bar(): A2<*>);
 // OK
-((new B3.bar(): B3<string>): A2<number>);
+((new B3().bar(): B3<string>): A2<number>);
 // error
-((new B3: A2<number>).qux(0): string); // error"
+((new B3(): A2<number>).qux(0): string); // error"
 `;
 
 exports[`test interface.js 1`] = `
@@ -294,8 +294,8 @@ class C {
   }
 }
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-(new DoublyLinkedList.prev(): DoublyLinkedList);
-(new DoublyLinkedList.next(): DoublyLinkedList);
+(new DoublyLinkedList().prev(): DoublyLinkedList);
+(new DoublyLinkedList().next(): DoublyLinkedList);
 
 var MiniImmutable = require(\"mini-immutable\");
 class C {
@@ -321,7 +321,7 @@ class A {
   // return of foo is not annotated to get around
   // substituting this below
   bar(): this {
-    return new A.foo();
+    return new A().foo();
   }
   // same as returning : A, so error
   qux(): this {
@@ -357,7 +357,7 @@ class A {
     // describes instances of A or subclasses of A: the
     // meaning of the \`this\` type is not changed simply by
     // switching into a static context
-    return new this; // but in a static context, the value \`this\` is bound to
+    return new this(); // but in a static context, the value \`this\` is bound to
     // the class, instead of instances of the class
   }
 }
@@ -451,7 +451,7 @@ class Base {
     return this;
   }
   qux() {
-    return new Base;
+    return new Base();
   }
 
   bar() {
@@ -474,22 +474,22 @@ class Override extends Base {
   }
   // OK, too
   bar() {
-    return new Override;
+    return new Override();
   } // OK (cf. error below)
 }
 
 class InheritOverride extends Override {}
 
-(new Inherit.foo(): Base);
-(new Inherit.foo(): Inherit);
+(new Inherit().foo(): Base);
+(new Inherit().foo(): Inherit);
 // error (cf. OK below)
-((new Inherit: Base).foo(): Base);
-(new Override.foo(): Base);
-(new Override.foo(): Override);
+((new Inherit(): Base).foo(): Base);
+(new Override().foo(): Base);
+(new Override().foo(): Override);
 // OK
-((new Override: Base).foo(): Base);
+((new Override(): Base).foo(): Base);
 
-(new InheritOverride.bar_caller(): InheritOverride);
+(new InheritOverride().bar_caller(): InheritOverride);
 // error
 // blame flips below
 // Examples with \`this\` types (compare with examples above)
@@ -498,7 +498,7 @@ class Base2 {
     return this;
   }
   qux(): Base2 {
-    return new Base2;
+    return new Base2();
   }
 
   bar(): this {
@@ -524,7 +524,7 @@ class Override2 extends Base2 {
   }
   // OK, too
   bar(): Override2 {
-    return new Override2;
+    return new Override2();
   }
   // error (cf. OK above)
   // see exploit below
@@ -536,16 +536,16 @@ class Override2 extends Base2 {
 
 class InheritOverride2 extends Override2 {}
 
-(new Inherit2.foo(): Base2);
-(new Inherit2.foo(): Inherit2);
+(new Inherit2().foo(): Base2);
+(new Inherit2().foo(): Inherit2);
 // OK (cf. error above)
-((new Inherit2: Base2).foo(): Base2);
-(new Override2.foo(): Base2);
-(new Override2.foo(): Override2);
+((new Inherit2(): Base2).foo(): Base2);
+(new Override2().foo(): Base2);
+(new Override2().foo(): Override2);
 // OK
-((new Override2: Base2).foo(): Base2);
+((new Override2(): Base2).foo(): Base2);
 
-(new InheritOverride2.bar_caller(): InheritOverride2);
+(new InheritOverride2().bar_caller(): InheritOverride2);
 // exploits error above
-(new Override2: Base2).corge(new Base2); // exploits error above"
+(new Override2(): Base2).corge(new Base2()); // exploits error above"
 `;
diff --git a/tests/throw/__snapshots__/jsfmt.spec.js.snap b/tests/throw/__snapshots__/jsfmt.spec.js.snap
index c03fa49e..f569336a 100644
--- a/tests/throw/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/throw/__snapshots__/jsfmt.spec.js.snap
@@ -27,12 +27,12 @@ function h(x: number): string {
  */
 
 function f(): number {
-  throw new Error; // OK to not return
+  throw new Error(); // OK to not return
 }
 
 function g(a: ?string) {
   if (a == null) {
-    throw new Error;
+    throw new Error();
   }
   return a * 1; // a is not null
 }
@@ -41,7 +41,7 @@ function h(x: number): string {
   if (x) {
     return \"foo\";
   } else {
-    throw new Error;
+    throw new Error();
   }
 }"
 `;
diff --git a/tests/traits/__snapshots__/jsfmt.spec.js.snap b/tests/traits/__snapshots__/jsfmt.spec.js.snap
index 8367f69b..026a3ea7 100644
--- a/tests/traits/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/traits/__snapshots__/jsfmt.spec.js.snap
@@ -35,11 +35,11 @@ declare class Baz<T> {
   x: T
 }
 
-(new Foo.x: number);
+(new Foo().x: number);
 // error: Qux wins
-(new Foo.y: string);
+(new Foo().y: string);
 // error: Bar wins
-(new Foo.z: number); // error: Qux wins"
+(new Foo().z: number); // error: Qux wins"
 `;
 
 exports[`test test2.js 1`] = `
diff --git a/tests/try/__snapshots__/jsfmt.spec.js.snap b/tests/try/__snapshots__/jsfmt.spec.js.snap
index b84b6763..bc20e064 100644
--- a/tests/try/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/try/__snapshots__/jsfmt.spec.js.snap
@@ -329,7 +329,7 @@ function f(b) {
   try {
     var x: number;
     if (b) {
-      throw new Error;
+      throw new Error();
     }
     x = 0;
   } catch (e) {}
diff --git a/tests/type-at-pos/__snapshots__/jsfmt.spec.js.snap b/tests/type-at-pos/__snapshots__/jsfmt.spec.js.snap
index 65500195..3d705615 100644
--- a/tests/type-at-pos/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/type-at-pos/__snapshots__/jsfmt.spec.js.snap
@@ -92,22 +92,22 @@ mn;
 // @flow
 
 class C<X> {}
-var cn: C<number> = new C;
+var cn: C<number> = new C();
 cn;
 
 function foo() {
   return C;
 }
 var D = foo();
-var dn: D<number> = new C;
+var dn: D<number> = new C();
 dn;
 
 type E<X> = C<X>;
-var en: E<number> = new C;
+var en: E<number> = new C();
 en;
 
 type F<X> = C<void>;
-var fn: F<number> = new C;
+var fn: F<number> = new C();
 fn;
 
 type O<X> = { x: X };
@@ -115,7 +115,7 @@ var on: O<number> = { x: 0 };
 on;
 
 type Mono = C<void>;
-var mn: Mono<number> = new C;
+var mn: Mono<number> = new C();
 // error: application of non-poly type
 mn;"
 `;
diff --git a/tests/type_only_vars/__snapshots__/jsfmt.spec.js.snap b/tests/type_only_vars/__snapshots__/jsfmt.spec.js.snap
index 7bbb3d28..50fee24d 100644
--- a/tests/type_only_vars/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/type_only_vars/__snapshots__/jsfmt.spec.js.snap
@@ -102,9 +102,9 @@ var n = Foo;
 var o = Baz;
 
 // errors from value positions only
-var a: Foo = new Foo;
-var b: Foo = new A.Foo;
-(new A.Bar: Baz);"
+var a: Foo = new Foo();
+var b: Foo = new A.Foo();
+(new A.Bar(): Baz);"
 `;
 
 exports[`test import_type.js 1`] = `
@@ -141,8 +141,8 @@ var n = Foo;
 var o = Baz;
 
 // But using it in a type should still work
-var a: Foo = new actualA.Foo;
-(new actualA.Bar: Baz);"
+var a: Foo = new actualA.Foo();
+(new actualA.Bar(): Baz);"
 `;
 
 exports[`test type_alias.js 1`] = `
diff --git a/tests/type_param_defaults/__snapshots__/jsfmt.spec.js.snap b/tests/type_param_defaults/__snapshots__/jsfmt.spec.js.snap
index 44022c8e..b8c7f197 100644
--- a/tests/type_param_defaults/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/type_param_defaults/__snapshots__/jsfmt.spec.js.snap
@@ -78,7 +78,7 @@ class A<T> {
 class B<T=string> extends A<T> {}
 
 var b_number: B<number> = new B(123);
-var b_void: B<void> = new B;
+var b_void: B<void> = new B();
 var b_default: B<> = new B(\"hello\");
 
 var b_star: B<*> = new B(123);
@@ -95,7 +95,7 @@ class C<T: ?string=string> extends A<T> {}
 
 var c_number: C<number> = new C(123);
 // Error number ~> ?string
-var c_void: C<void> = new C;
+var c_void: C<void> = new C();
 var c_default: C<> = new C(\"hello\");
 var c_star: C<*> = new C(\"hello\");
 
@@ -107,7 +107,7 @@ var c_star: C<*> = new C(\"hello\");
 // Error string ~> boolean
 class D<S, T=string> extends A<T> {}
 var d_number: D<mixed, number> = new D(123);
-var d_void: D<mixed, void> = new D;
+var d_void: D<mixed, void> = new D();
 var d_default: D<mixed> = new D(\"hello\");
 var d_too_few_args: D<> = new D(\"hello\");
 // Error too few tparams
@@ -139,7 +139,7 @@ class I<T: ?string=*> extends A<T> {}
 
 var i_number: I<number> = new I(123);
 // Error number ~> ?string
-var i_void: I<void> = new I;
+var i_void: I<void> = new I();
 var i_default: I<> = new I(\"hello\");
 var i_star: I<*> = new I(\"hello\");"
 `;
diff --git a/tests/typeof/__snapshots__/jsfmt.spec.js.snap b/tests/typeof/__snapshots__/jsfmt.spec.js.snap
index 3440773f..05585e78 100644
--- a/tests/typeof/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/typeof/__snapshots__/jsfmt.spec.js.snap
@@ -102,7 +102,7 @@ class MyClass1 {
 // an object produced by the MyClass1 constructor
 // function.
 //
-var a: MyClass1 = new MyClass1;
+var a: MyClass1 = new MyClass1();
 
 // Following tests are errors which conflate the type
 // of the class value itself with the type of its
@@ -136,7 +136,7 @@ class MyClass2 {
 // to a variable whose annotated type is the type of
 // the class value (constructor function) MyClass2 itself.
 //
-var c: typeof MyClass2 = new MyClass2;
+var c: typeof MyClass2 = new MyClass2();
 
 //////////////////////////////////////
 // == typeof <<non-class value>> == //
diff --git a/tests/union/__snapshots__/jsfmt.spec.js.snap b/tests/union/__snapshots__/jsfmt.spec.js.snap
index 9f5aba92..159b375a 100644
--- a/tests/union/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/union/__snapshots__/jsfmt.spec.js.snap
@@ -116,7 +116,7 @@ var foo = new Foo();
 var foostr: Foo | string = foo;
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 var Foo = require(\"./issue-323-lib\");
-var foo = new Foo;
+var foo = new Foo();
 var foostr: Foo | string = foo;"
 `;
 
@@ -145,8 +145,8 @@ class Foo {}
 
 class Bar {}
 
-var foostr: Foo | string = new Foo;
-var barstr: Bar | string = new Bar;
+var foostr: Foo | string = new Foo();
+var barstr: Bar | string = new Bar();
 
 foostr = barstr;"
 `;
@@ -177,7 +177,7 @@ class Tag {
 type Node = Tag_ | string;
 class Tag_ {
   constructor() {
-    var a1: Array<Node> = [ new Tag_ ];
+    var a1: Array<Node> = [ new Tag_() ];
     var a2: Array<Node> = a1;
   }
 }"
@@ -402,19 +402,19 @@ class C {}
 class D {}
 function CD(b) {
   var E = b ? C : D;
-  var c: C = new E;
+  var c: C = new E();
   // error, since E could be D, and D is not a subtype of C
   function qux(e: E) {}
   // this annotation is an error: is it C, or is it D?
   function qux2(e: C | D) {}
   // OK
-  qux2(new C);
+  qux2(new C());
 }
 
 declare class F { foo(x: number): void, foo(x: string): void }
 function corge(b) {
   var x = b ? \"\" : 0;
-  new F.foo(x);
+  new F().foo(x);
 }"
 `;
 
diff --git a/tests/union_new/__snapshots__/jsfmt.spec.js.snap b/tests/union_new/__snapshots__/jsfmt.spec.js.snap
index fec9b8f8..e2ebbb3e 100644
--- a/tests/union_new/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/union_new/__snapshots__/jsfmt.spec.js.snap
@@ -484,7 +484,7 @@ function inst(a: A5 | A6) {}
 
 class B5 {}
 class B6 {}
-inst([ new B6 ]);
+inst([ new B6() ]);
 
 type A5 = B5[];
 type A6 = B6[];"
@@ -605,7 +605,7 @@ class C<X> {}
 
 function inst(a: C<number> | C<string>) {}
 
-inst((new C: A3));
+inst((new C(): A3));
 
 type A3 = C<B3>;
 
@@ -1150,10 +1150,10 @@ class D {}
 function check_inst(_: C | D) {}
 
 // ok
-check_inst(new D);
+check_inst(new D());
 
 // ...even when they \"flow\" in
-check_inst(id(new C));
+check_inst(id(new C()));
 
 ////////////////////////
 // function annotations
@@ -1192,7 +1192,7 @@ class P<X> {}
 function check_poly_inst(_: P<number> | P<string>) {}
 
 // help!
-check_poly_inst(new P);"
+check_poly_inst(new P());"
 `;
 
 exports[`test test11.js 1`] = `
@@ -1445,7 +1445,7 @@ function f() {
   return 0;
 }
 
-new C.m(f());"
+new C().m(f());"
 `;
 
 exports[`test test19.js 1`] = `
@@ -1467,7 +1467,7 @@ declare class D {
 // constructor overloads
 
 function m<X>() {
-  return new D;
+  return new D();
 }
 
 declare class D { constructor(_: void): void, constructor(_: null): void }"
@@ -1758,7 +1758,7 @@ declare class Record {
   set(x: \"bar\", y: string): void
 }
 
-new Record.set(\"foo\", \"42\");"
+new Record().set(\"foo\", \"42\");"
 `;
 
 exports[`test test27.js 1`] = `
@@ -1957,7 +1957,7 @@ declare class ImmutableMap<K, V> {}
 declare function convert<K, V>(iter: SomeIterable<[K, V]>): ImmutableMap<K, V>;
 
 function foo(): ImmutableMap<string, boolean> {
-  const countersGlobalMap = new SomeMap;
+  const countersGlobalMap = new SomeMap();
   countersGlobalMap.set(\"\", false);
   return convert(countersGlobalMap);
 }"
diff --git a/tests/while/__snapshots__/jsfmt.spec.js.snap b/tests/while/__snapshots__/jsfmt.spec.js.snap
index d07f7c7b..a4acff0c 100644
--- a/tests/while/__snapshots__/jsfmt.spec.js.snap
+++ b/tests/while/__snapshots__/jsfmt.spec.js.snap
@@ -57,11 +57,11 @@ while (node) {
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 class C {
   m() {
-    return new C;
+    return new C();
   }
 }
 function blah() {}
-var node: ?C = new C;
+var node: ?C = new C();
 while (node) {
   var parent = node.m();
   var cloneable: C = node;