diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index 82b4a3fb59f..3a8ecb20999 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -3645,7 +3645,7 @@ namespace ts {
                         return { value: o && o[i++], done: !o };
                     }
                 };
-                throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+                throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
             };`
     };
 
diff --git a/src/testRunner/unittests/evaluation/forOf.ts b/src/testRunner/unittests/evaluation/forOf.ts
index 3d9352cf926..9efdf16d351 100644
--- a/src/testRunner/unittests/evaluation/forOf.ts
+++ b/src/testRunner/unittests/evaluation/forOf.ts
@@ -66,7 +66,7 @@ describe("unittests:: evaluation:: forOfEvaluation", () => {
         }
         `, { downlevelIteration: true, target: ts.ScriptTarget.ES5 });
 
-        assert.throws(() => result.main(), "undefined is not iterable (cannot read property Symbol(Symbol.iterator))");
+        assert.throws(() => result.main(), /cannot read property.*Symbol\(Symbol\.iterator\).*/i);
     });
 
     it("es5 over object with no Symbol.iterator with no Symbol", () => {
@@ -93,7 +93,7 @@ describe("unittests:: evaluation:: forOfEvaluation", () => {
         }
         `, { downlevelIteration: true, target: ts.ScriptTarget.ES5 });
 
-        assert.throws(() => result.main(), "Object not iterable");
+        assert.throws(() => result.main(), "Object is not iterable");
     });
 
     it("es5 over object with Symbol.iterator", () => {
@@ -110,7 +110,7 @@ describe("unittests:: evaluation:: forOfEvaluation", () => {
                 {
                     output.push(value)
                 }
-                
+
             }`, { downlevelIteration: true, target: ts.ScriptTarget.ES5 });
 
         result.main();
diff --git a/tests/baselines/reference/ES5For-of33.js b/tests/baselines/reference/ES5For-of33.js
index 900f32b6407..e177630b00c 100644
--- a/tests/baselines/reference/ES5For-of33.js
+++ b/tests/baselines/reference/ES5For-of33.js
@@ -13,7 +13,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var e_1, _a;
 try {
diff --git a/tests/baselines/reference/ES5For-of33.sourcemap.txt b/tests/baselines/reference/ES5For-of33.sourcemap.txt
index f6be2e8fb11..b1be3f06d45 100644
--- a/tests/baselines/reference/ES5For-of33.sourcemap.txt
+++ b/tests/baselines/reference/ES5For-of33.sourcemap.txt
@@ -17,7 +17,7 @@ sourceFile:ES5For-of33.ts
 >>>            return { value: o && o[i++], done: !o };
 >>>        }
 >>>    };
->>>    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+>>>    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 >>>};
 >>>var e_1, _a;
 >>>try {
diff --git a/tests/baselines/reference/ES5For-of34.js b/tests/baselines/reference/ES5For-of34.js
index d4ab664d009..2f0ee24e3d8 100644
--- a/tests/baselines/reference/ES5For-of34.js
+++ b/tests/baselines/reference/ES5For-of34.js
@@ -16,7 +16,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var e_1, _a;
 function foo() {
diff --git a/tests/baselines/reference/ES5For-of34.sourcemap.txt b/tests/baselines/reference/ES5For-of34.sourcemap.txt
index e64aa5cdb8c..5694d550cf6 100644
--- a/tests/baselines/reference/ES5For-of34.sourcemap.txt
+++ b/tests/baselines/reference/ES5For-of34.sourcemap.txt
@@ -17,7 +17,7 @@ sourceFile:ES5For-of34.ts
 >>>            return { value: o && o[i++], done: !o };
 >>>        }
 >>>    };
->>>    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+>>>    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 >>>};
 >>>var e_1, _a;
 >>>function foo() {
diff --git a/tests/baselines/reference/ES5For-of35.js b/tests/baselines/reference/ES5For-of35.js
index 1158ae5ede1..fb0ac5d2d2b 100644
--- a/tests/baselines/reference/ES5For-of35.js
+++ b/tests/baselines/reference/ES5For-of35.js
@@ -14,7 +14,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var e_1, _a;
 try {
diff --git a/tests/baselines/reference/ES5For-of35.sourcemap.txt b/tests/baselines/reference/ES5For-of35.sourcemap.txt
index 1cabb7af3b6..004c84a7ddf 100644
--- a/tests/baselines/reference/ES5For-of35.sourcemap.txt
+++ b/tests/baselines/reference/ES5For-of35.sourcemap.txt
@@ -17,7 +17,7 @@ sourceFile:ES5For-of35.ts
 >>>            return { value: o && o[i++], done: !o };
 >>>        }
 >>>    };
->>>    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+>>>    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 >>>};
 >>>var e_1, _a;
 >>>try {
diff --git a/tests/baselines/reference/ES5For-of36.js b/tests/baselines/reference/ES5For-of36.js
index f08a178256d..da5d6b854e3 100644
--- a/tests/baselines/reference/ES5For-of36.js
+++ b/tests/baselines/reference/ES5For-of36.js
@@ -14,7 +14,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var __read = (this && this.__read) || function (o, n) {
     var m = typeof Symbol === "function" && o[Symbol.iterator];
diff --git a/tests/baselines/reference/ES5For-of36.sourcemap.txt b/tests/baselines/reference/ES5For-of36.sourcemap.txt
index b1977e55d81..21d86faad16 100644
--- a/tests/baselines/reference/ES5For-of36.sourcemap.txt
+++ b/tests/baselines/reference/ES5For-of36.sourcemap.txt
@@ -17,7 +17,7 @@ sourceFile:ES5For-of36.ts
 >>>            return { value: o && o[i++], done: !o };
 >>>        }
 >>>    };
->>>    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+>>>    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 >>>};
 >>>var __read = (this && this.__read) || function (o, n) {
 >>>    var m = typeof Symbol === "function" && o[Symbol.iterator];
diff --git a/tests/baselines/reference/ES5For-of37.js b/tests/baselines/reference/ES5For-of37.js
index ada2710249f..7b4baf8f9a0 100644
--- a/tests/baselines/reference/ES5For-of37.js
+++ b/tests/baselines/reference/ES5For-of37.js
@@ -26,7 +26,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var e_1, _a, e_2, _b;
 try {
diff --git a/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator.js b/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator.js
index a0bc036f2a7..21b47adf6c7 100644
--- a/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator.js
+++ b/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator.js
@@ -43,7 +43,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 function a() {
     var _loop_1, _a, _b, i, e_1_1;
diff --git a/tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.js b/tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.js
index 629cd3b0d9b..fa9c9f3a515 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.classMethods.es5.js
@@ -291,7 +291,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var C4 = /** @class */ (function () {
     function C4() {
@@ -373,7 +373,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var C5 = /** @class */ (function () {
     function C5() {
diff --git a/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.js b/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.js
index 622195d09df..ba9e6b4180e 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.functionDeclarations.es5.js
@@ -245,7 +245,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 function f4() {
     return __asyncGenerator(this, arguments, function f4_1() {
@@ -322,7 +322,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 function f5() {
     return __asyncGenerator(this, arguments, function f5_1() {
diff --git a/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.js b/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.js
index 7d8b9ad649b..bd1280df237 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.functionExpressions.es5.js
@@ -245,7 +245,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var f4 = function () {
     return __asyncGenerator(this, arguments, function () {
@@ -322,7 +322,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var f5 = function () {
     return __asyncGenerator(this, arguments, function () {
diff --git a/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es5.js b/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es5.js
index 8677898f05d..138c729aa29 100644
--- a/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es5.js
+++ b/tests/baselines/reference/emitter.asyncGenerators.objectLiteralMethods.es5.js
@@ -265,7 +265,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var o4 = {
     f: function () {
@@ -344,7 +344,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 var o5 = {
     f: function () {
diff --git a/tests/baselines/reference/emptyVariableDeclarationBindingPatterns01_ES5iterable.js b/tests/baselines/reference/emptyVariableDeclarationBindingPatterns01_ES5iterable.js
index e1a2a828b5c..bace5a52d95 100644
--- a/tests/baselines/reference/emptyVariableDeclarationBindingPatterns01_ES5iterable.js
+++ b/tests/baselines/reference/emptyVariableDeclarationBindingPatterns01_ES5iterable.js
@@ -74,7 +74,7 @@ var __values = (this && this.__values) || function(o) {
             return { value: o && o[i++], done: !o };
         }
     };
-    throw new TypeError(s ? "Object not iterable." : "Symbol.iterator is not defined.");
+    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
 };
 (function () {
     var a;