diff --git a/bin/prettier.js b/bin/prettier.js
index dc854742..9599e88c 100755
--- a/bin/prettier.js
+++ b/bin/prettier.js
@@ -139,13 +139,94 @@ function format(input) {
   }
 
   if (argv["debug-check"]) {
+    function massageAST(ast) {
+      if (Array.isArray(ast)) {
+        return ast.map(e => massageAST(e)).filter(e => e);
+      }
+      if (ast && typeof ast === "object") {
+        // We remove extra `;` and add them when needed
+        if (ast.type === "EmptyStatement") {
+          return undefined;
+        }
+
+        // We move text around, including whitespaces and add {" "}
+        if (ast.type === "JSXText") {
+          return undefined;
+        }
+        if (
+          ast.type === "JSXExpressionContainer" &&
+          ast.expression.type === "Literal" &&
+          ast.expression.value === " "
+        ) {
+          return undefined;
+        }
+
+        const newObj = {};
+        for (var key in ast) {
+          newObj[key] = massageAST(ast[key]);
+        }
+
+        [
+          "loc",
+          "range",
+          "raw",
+          "comments",
+          "start",
+          "end",
+          "tokens",
+          "flags"
+        ].forEach(name => {
+          delete newObj[name];
+        });
+
+        // We convert <div></div> to <div />
+        if (ast.type === "JSXOpeningElement") {
+          delete newObj.selfClosing;
+        }
+        if (ast.type === "JSXElement") {
+          delete newObj.closingElement;
+        }
+
+        // We change {'key': value} into {key: value}
+        if (
+          ast.type === "Property" &&
+          typeof ast.key === "object" &&
+          ast.key &&
+          (ast.key.type === "Literal" || ast.key.type === "Identifier")
+        ) {
+          delete newObj.key;
+        }
+
+        return newObj;
+      }
+      return ast;
+    }
+
+    function cleanAST(ast) {
+      return JSON.stringify(massageAST(ast), null, 2);
+    }
+
+    function diff(a, b) {
+      return require("diff")
+        .createTwoFilesPatch("", "", a, b, "", "", { context: 2 });
+    }
+
     const pp = prettier.format(input, options);
     const pppp = prettier.format(pp, options);
     if (pp !== pppp) {
-      const diff = require(
-        "diff"
-      ).createTwoFilesPatch("", "", pp, pppp, "", "", { context: 2 });
-      console.error(diff);
+      process.stdout.write("\n");
+      console.error('prettier(input) !== prettier(prettier(input))');
+      console.error(diff(pp, pppp));
+    } else {
+      const ast = cleanAST(prettier.__debug.parse(input, options));
+      const past = cleanAST(prettier.__debug.parse(pp, options));
+
+      if (ast !== past) {
+        process.stdout.write("\n");
+        console.error('ast(input) !== ast(prettier(input))');
+        console.error(diff(ast, past));
+        console.error(diff(input, pp));
+      }
     }
     return;
   }
diff --git a/index.js b/index.js
index b455bba1..e6348e70 100644
--- a/index.js
+++ b/index.js
@@ -114,6 +114,9 @@ module.exports = {
   },
   version: version,
   __debug: {
+    parse: function(text, opts) {
+      return parse(text, opts);
+    },
     formatAST: function(ast, opts) {
       opts = normalizeOptions(opts);
       const doc = printAstToDoc(ast, opts);