diff --git a/tests/baselines/reference/typeGuardsDefeat.js b/tests/baselines/reference/typeGuardsDefeat.js
new file mode 100644
index 0000000000..b5e1e0c362
--- /dev/null
+++ b/tests/baselines/reference/typeGuardsDefeat.js
@@ -0,0 +1,75 @@
+//// [typeGuardsDefeat.ts]
+// Also note that it is possible to defeat a type guard by calling a function that changes the 
+// type of the guarded variable.
+function foo(x: number | string) {
+    function f() {
+        x = 10;
+    }
+    if (typeof x === "string") {
+        f();
+        return x.length; // string
+    }
+    else {
+        return x++; // number
+    }
+}
+function foo2(x: number | string) {
+    if (typeof x === "string") {
+        return x.length; // string
+    }
+    else {
+        (function f() {
+            x = 10;
+        })();
+        return x++; // number
+    }
+}
+function foo3(x: number | string) {
+    if (typeof x === "string") {
+        return x.length; // string
+    }
+    else {
+        (() => {
+            x = 10;
+        })();
+        return x++; // number
+    }
+}
+
+//// [typeGuardsDefeat.js]
+// Also note that it is possible to defeat a type guard by calling a function that changes the 
+// type of the guarded variable.
+function foo(x) {
+    function f() {
+        x = 10;
+    }
+    if (typeof x === "string") {
+        f();
+        return x.length; // string
+    }
+    else {
+        return x++; // number
+    }
+}
+function foo2(x) {
+    if (typeof x === "string") {
+        return x.length; // string
+    }
+    else {
+        (function f() {
+            x = 10;
+        })();
+        return x++; // number
+    }
+}
+function foo3(x) {
+    if (typeof x === "string") {
+        return x.length; // string
+    }
+    else {
+        (function () {
+            x = 10;
+        })();
+        return x++; // number
+    }
+}
diff --git a/tests/baselines/reference/typeGuardsDefeat.types b/tests/baselines/reference/typeGuardsDefeat.types
new file mode 100644
index 0000000000..6c4153cc3e
--- /dev/null
+++ b/tests/baselines/reference/typeGuardsDefeat.types
@@ -0,0 +1,95 @@
+=== tests/cases/conformance/expressions/typeGuards/typeGuardsDefeat.ts ===
+// Also note that it is possible to defeat a type guard by calling a function that changes the 
+// type of the guarded variable.
+function foo(x: number | string) {
+>foo : (x: string | number) => number
+>x : string | number
+
+    function f() {
+>f : () => void
+
+        x = 10;
+>x = 10 : number
+>x : string | number
+    }
+    if (typeof x === "string") {
+>typeof x === "string" : boolean
+>typeof x : string
+>x : string | number
+
+        f();
+>f() : void
+>f : () => void
+
+        return x.length; // string
+>x.length : number
+>x : string
+>length : number
+    }
+    else {
+        return x++; // number
+>x++ : number
+>x : number
+    }
+}
+function foo2(x: number | string) {
+>foo2 : (x: string | number) => number
+>x : string | number
+
+    if (typeof x === "string") {
+>typeof x === "string" : boolean
+>typeof x : string
+>x : string | number
+
+        return x.length; // string
+>x.length : number
+>x : string
+>length : number
+    }
+    else {
+        (function f() {
+>(function f() {            x = 10;        })() : void
+>(function f() {            x = 10;        }) : () => void
+>function f() {            x = 10;        } : () => void
+>f : () => void
+
+            x = 10;
+>x = 10 : number
+>x : string | number
+
+        })();
+        return x++; // number
+>x++ : number
+>x : number
+    }
+}
+function foo3(x: number | string) {
+>foo3 : (x: string | number) => number
+>x : string | number
+
+    if (typeof x === "string") {
+>typeof x === "string" : boolean
+>typeof x : string
+>x : string | number
+
+        return x.length; // string
+>x.length : number
+>x : string
+>length : number
+    }
+    else {
+        (() => {
+>(() => {            x = 10;        })() : void
+>(() => {            x = 10;        }) : () => void
+>() => {            x = 10;        } : () => void
+
+            x = 10;
+>x = 10 : number
+>x : string | number
+
+        })();
+        return x++; // number
+>x++ : number
+>x : number
+    }
+}
diff --git a/tests/cases/conformance/expressions/typeGuards/typeGuardsDefeat.ts b/tests/cases/conformance/expressions/typeGuards/typeGuardsDefeat.ts
new file mode 100644
index 0000000000..9c78e72539
--- /dev/null
+++ b/tests/cases/conformance/expressions/typeGuards/typeGuardsDefeat.ts
@@ -0,0 +1,36 @@
+// Also note that it is possible to defeat a type guard by calling a function that changes the 
+// type of the guarded variable.
+function foo(x: number | string) {
+    function f() {
+        x = 10;
+    }
+    if (typeof x === "string") {
+        f();
+        return x.length; // string
+    }
+    else {
+        return x++; // number
+    }
+}
+function foo2(x: number | string) {
+    if (typeof x === "string") {
+        return x.length; // string
+    }
+    else {
+        (function f() {
+            x = 10;
+        })();
+        return x++; // number
+    }
+}
+function foo3(x: number | string) {
+    if (typeof x === "string") {
+        return x.length; // string
+    }
+    else {
+        (() => {
+            x = 10;
+        })();
+        return x++; // number
+    }
+}
\ No newline at end of file