diff --git a/src/generators/jsonSchema.js b/src/generators/jsonSchema.js
index 9c448e3..f1b5e39 100644
--- a/src/generators/jsonSchema.js
+++ b/src/generators/jsonSchema.js
@@ -122,9 +122,11 @@ function convert(fund: Fund, type: ?Type): Schema {
                 oneOf: [convert(fund, type.value), {type: 'null'}],
             };
         case 'number':
-            return {
-                type: type.repr === 'f32' || type.repr === 'f64' ? 'number' : 'integer',
-            };
+            const {repr} = type;
+
+            return repr === 'f32' || repr === 'f64' ? {type: 'number'}
+                 : repr === 'i32' || repr === 'i64' ? {type: 'integer'}
+                 : {type: 'integer', minimum: 0};
         case 'string':
             return {
                 type: 'string',
diff --git a/tests/samples/pragmas/schema.json b/tests/samples/pragmas/schema.json
index 8ebf6b1..43aa735 100644
--- a/tests/samples/pragmas/schema.json
+++ b/tests/samples/pragmas/schema.json
@@ -7,9 +7,11 @@
                 "a": {"type": "integer"},
                 "b": {"type": "integer"},
                 "c": {"type": "number"},
-                "d": {"type": "number"}
+                "d": {"type": "number"},
+                "e": {"type": "integer", "minimum": 0},
+                "f": {"type": "integer", "minimum": 0}
             },
-            "required": ["a", "b", "c", "d"]
+            "required": ["a", "b", "c", "d", "e", "f"]
         },
         "pragmas::Interface": {
             "type": "object",
@@ -18,9 +20,11 @@
                 "b": {"type": "integer"},
                 "c": {"type": "number"},
                 "d": {"type": "number"},
-                "e": {"type": "string"}
+                "e": {"type": "integer", "minimum": 0},
+                "f": {"type": "integer", "minimum": 0},
+                "g": {"type": "string"}
             },
-            "required": ["a", "b", "c", "d", "e"]
+            "required": ["a", "b", "c", "d", "e", "f", "g"]
         },
         "pragmas::Class": {
             "type": "object",
@@ -28,9 +32,11 @@
                 "a": {"type": "integer"},
                 "b": {"type": "integer"},
                 "c": {"type": "number"},
-                "d": {"type": "number"}
+                "d": {"type": "number"},
+                "e": {"type": "integer", "minimum": 0},
+                "f": {"type": "integer", "minimum": 0}
             },
-            "required": ["a", "b", "c", "d"]
+            "required": ["a", "b", "c", "d", "e", "f"]
         }
     }
 }
diff --git a/tests/samples/pragmas/source.js b/tests/samples/pragmas/source.js
index ef8fec9..2f13709 100644
--- a/tests/samples/pragmas/source.js
+++ b/tests/samples/pragmas/source.js
@@ -7,6 +7,10 @@ type Type = {
     c: number,
     // @repr {f64}
     d: number,
+    // @repr {u32}
+    e: number,
+    // @repr {u64}
+    f: number,
 };
 
 interface Interface {
@@ -18,9 +22,13 @@ interface Interface {
     c: number;
     // @repr {f64}
     d: number;
+    // @repr {u32}
+    e: number;
+    // @repr {u64}
+    f: number;
 
     // Some comment.
-    e: string;
+    g: string;
 }
 
 class Class {
@@ -32,6 +40,10 @@ class Class {
     c: number;
     // @repr {f64}
     d: number;
+    // @repr {u32}
+    e: number;
+    // @repr {u64}
+    f: number;
 }
 
 export {Type, Interface, Class};
diff --git a/tests/samples/pragmas/types.yaml b/tests/samples/pragmas/types.yaml
index c71f34d..e6709ee 100644
--- a/tests/samples/pragmas/types.yaml
+++ b/tests/samples/pragmas/types.yaml
@@ -12,6 +12,12 @@
     -   name: d
         value: {kind: number, repr: f64}
         required: true
+    -   name: e
+        value: {kind: number, repr: u32}
+        required: true
+    -   name: f
+        value: {kind: number, repr: u64}
+        required: true
     id: [pragmas, Type]
 -   kind: record
     fields:
@@ -28,6 +34,12 @@
         value: {kind: number, repr: f64}
         required: true
     -   name: e
+        value: {kind: number, repr: u32}
+        required: true
+    -   name: f
+        value: {kind: number, repr: u64}
+        required: true
+    -   name: g
         value: {kind: string}
         required: true
     id: [pragmas, Interface]
@@ -45,4 +57,10 @@
     -   name: d
         value: {kind: number, repr: f64}
         required: true
+    -   name: e
+        value: {kind: number, repr: u32}
+        required: true
+    -   name: f
+        value: {kind: number, repr: u64}
+        required: true
     id: [pragmas, Class]