diff --git a/tests/baselines/reference/undefinedTypeAssignment.errors.txt b/tests/baselines/reference/undefinedTypeAssignment.errors.txt
deleted file mode 100644
index 0b4a8eff874..00000000000
--- a/tests/baselines/reference/undefinedTypeAssignment.errors.txt
+++ /dev/null
@@ -1,43 +0,0 @@
-tests/cases/compiler/a.ts(1,1): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-tests/cases/compiler/a.ts(2,5): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-tests/cases/compiler/a.ts(3,5): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-tests/cases/compiler/b.ts(1,7): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-tests/cases/compiler/b.ts(4,11): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-tests/cases/compiler/b.ts(7,11): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-tests/cases/compiler/b.ts(10,8): error TS2304: Cannot find name 'undefined'.
-
-
-==== tests/cases/compiler/a.ts (3 errors) ====
-    type undefined = string;
-    ~~~~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-    var undefined = void 0;
-        ~~~~~~~~~
-!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-    var undefined = null;
-        ~~~~~~~~~
-!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-    function p(undefined = 42) {
-    	return undefined;
-    }
-==== tests/cases/compiler/b.ts (4 errors) ====
-    class undefined {
-          ~~~~~~~~~
-!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-    	foo: string;
-    }
-    interface undefined {
-              ~~~~~~~~~
-!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-    	member: number;
-    }
-    namespace undefined {
-              ~~~~~~~~~
-!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
-    	export var x = 42;
-    }
-    var x: undefined;
-           ~~~~~~~~~
-!!! error TS2304: Cannot find name 'undefined'.
-    var x: typeof undefined;
-    
\ No newline at end of file
diff --git a/tests/baselines/reference/undefinedTypeAssignment.js b/tests/baselines/reference/undefinedTypeAssignment.js
deleted file mode 100644
index 9b4106c18ea..00000000000
--- a/tests/baselines/reference/undefinedTypeAssignment.js
+++ /dev/null
@@ -1,42 +0,0 @@
-//// [tests/cases/compiler/undefinedTypeAssignment.ts] ////
-
-//// [a.ts]
-type undefined = string;
-var undefined = void 0;
-var undefined = null;
-function p(undefined = 42) {
-	return undefined;
-}
-//// [b.ts]
-class undefined {
-	foo: string;
-}
-interface undefined {
-	member: number;
-}
-namespace undefined {
-	export var x = 42;
-}
-var x: undefined;
-var x: typeof undefined;
-
-
-//// [a.js]
-var undefined = void 0;
-var undefined = null;
-function p(undefined) {
-    if (undefined === void 0) { undefined = 42; }
-    return undefined;
-}
-//// [b.js]
-var undefined = (function () {
-    function undefined() {
-    }
-    return undefined;
-})();
-var undefined;
-(function (undefined) {
-    undefined.x = 42;
-})(undefined || (undefined = {}));
-var x;
-var x;
diff --git a/tests/baselines/reference/undefinedTypeAssignment1.errors.txt b/tests/baselines/reference/undefinedTypeAssignment1.errors.txt
new file mode 100644
index 00000000000..b8dd74a58a8
--- /dev/null
+++ b/tests/baselines/reference/undefinedTypeAssignment1.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/undefinedTypeAssignment1.ts(1,1): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+
+
+==== tests/cases/compiler/undefinedTypeAssignment1.ts (1 errors) ====
+    type undefined = string;
+    ~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+    function p(undefined = "wat") {
+    	return undefined;
+    }
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/undefinedTypeAssignment1.js b/tests/baselines/reference/undefinedTypeAssignment1.js
new file mode 100644
index 00000000000..1f53c4f6c45
--- /dev/null
+++ b/tests/baselines/reference/undefinedTypeAssignment1.js
@@ -0,0 +1,12 @@
+//// [undefinedTypeAssignment1.ts]
+type undefined = string;
+function p(undefined = "wat") {
+	return undefined;
+}
+
+
+//// [undefinedTypeAssignment1.js]
+function p(undefined) {
+    if (undefined === void 0) { undefined = "wat"; }
+    return undefined;
+}
diff --git a/tests/baselines/reference/undefinedTypeAssignment2.errors.txt b/tests/baselines/reference/undefinedTypeAssignment2.errors.txt
new file mode 100644
index 00000000000..55fdbf0fc1b
--- /dev/null
+++ b/tests/baselines/reference/undefinedTypeAssignment2.errors.txt
@@ -0,0 +1,8 @@
+tests/cases/compiler/undefinedTypeAssignment2.ts(1,5): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+
+
+==== tests/cases/compiler/undefinedTypeAssignment2.ts (1 errors) ====
+    var undefined = void 0;
+        ~~~~~~~~~
+!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/undefinedTypeAssignment2.js b/tests/baselines/reference/undefinedTypeAssignment2.js
new file mode 100644
index 00000000000..040bc8c800d
--- /dev/null
+++ b/tests/baselines/reference/undefinedTypeAssignment2.js
@@ -0,0 +1,6 @@
+//// [undefinedTypeAssignment2.ts]
+var undefined = void 0;
+
+
+//// [undefinedTypeAssignment2.js]
+var undefined = void 0;
diff --git a/tests/baselines/reference/undefinedTypeAssignment3.errors.txt b/tests/baselines/reference/undefinedTypeAssignment3.errors.txt
new file mode 100644
index 00000000000..88df370940f
--- /dev/null
+++ b/tests/baselines/reference/undefinedTypeAssignment3.errors.txt
@@ -0,0 +1,8 @@
+tests/cases/compiler/undefinedTypeAssignment3.ts(1,5): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+
+
+==== tests/cases/compiler/undefinedTypeAssignment3.ts (1 errors) ====
+    var undefined = null;
+        ~~~~~~~~~
+!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/undefinedTypeAssignment3.js b/tests/baselines/reference/undefinedTypeAssignment3.js
new file mode 100644
index 00000000000..4015d49e33a
--- /dev/null
+++ b/tests/baselines/reference/undefinedTypeAssignment3.js
@@ -0,0 +1,6 @@
+//// [undefinedTypeAssignment3.ts]
+var undefined = null;
+
+
+//// [undefinedTypeAssignment3.js]
+var undefined = null;
diff --git a/tests/baselines/reference/undefinedTypeAssignment4.errors.txt b/tests/baselines/reference/undefinedTypeAssignment4.errors.txt
new file mode 100644
index 00000000000..dab6ea2a880
--- /dev/null
+++ b/tests/baselines/reference/undefinedTypeAssignment4.errors.txt
@@ -0,0 +1,24 @@
+tests/cases/compiler/undefinedTypeAssignment4.ts(1,7): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+tests/cases/compiler/undefinedTypeAssignment4.ts(4,11): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+tests/cases/compiler/undefinedTypeAssignment4.ts(7,11): error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+
+
+==== tests/cases/compiler/undefinedTypeAssignment4.ts (3 errors) ====
+    class undefined {
+          ~~~~~~~~~
+!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+    	foo: string;
+    }
+    interface undefined {
+              ~~~~~~~~~
+!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+    	member: number;
+    }
+    namespace undefined {
+              ~~~~~~~~~
+!!! error TS2397: Declaration name conflicts with built-in global identifier 'undefined'.
+    	export var x = 42;
+    }
+    var x: undefined;
+    var y: typeof undefined;
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/undefinedTypeAssignment4.js b/tests/baselines/reference/undefinedTypeAssignment4.js
new file mode 100644
index 00000000000..186afd872c3
--- /dev/null
+++ b/tests/baselines/reference/undefinedTypeAssignment4.js
@@ -0,0 +1,26 @@
+//// [undefinedTypeAssignment4.ts]
+class undefined {
+	foo: string;
+}
+interface undefined {
+	member: number;
+}
+namespace undefined {
+	export var x = 42;
+}
+var x: undefined;
+var y: typeof undefined;
+
+
+//// [undefinedTypeAssignment4.js]
+var undefined = (function () {
+    function undefined() {
+    }
+    return undefined;
+})();
+var undefined;
+(function (undefined) {
+    undefined.x = 42;
+})(undefined || (undefined = {}));
+var x;
+var y;