diff --git a/lib/lib.d.ts b/lib/lib.d.ts
index 87280fedba4..922820b5d90 100644
--- a/lib/lib.d.ts
+++ b/lib/lib.d.ts
@@ -260,6 +260,9 @@ interface Function {
       */
     bind(this: Function, thisArg: any, ...argArray: any[]): any;
 
+    /** Returns a string representation of a function. */
+    toString(): string;
+
     prototype: any;
     readonly length: number;
 
diff --git a/lib/lib.es5.d.ts b/lib/lib.es5.d.ts
index d20c7d1e3a7..a13ffc92d04 100644
--- a/lib/lib.es5.d.ts
+++ b/lib/lib.es5.d.ts
@@ -260,6 +260,9 @@ interface Function {
       */
     bind(this: Function, thisArg: any, ...argArray: any[]): any;
 
+    /** Returns a string representation of a function. */
+    toString(): string;
+
     prototype: any;
     readonly length: number;
 
diff --git a/lib/lib.es6.d.ts b/lib/lib.es6.d.ts
index 6067d810b44..4c8806dd7dd 100644
--- a/lib/lib.es6.d.ts
+++ b/lib/lib.es6.d.ts
@@ -260,6 +260,9 @@ interface Function {
       */
     bind(this: Function, thisArg: any, ...argArray: any[]): any;
 
+    /** Returns a string representation of a function. */
+    toString(): string;
+
     prototype: any;
     readonly length: number;
 
diff --git a/lib/tsc.js b/lib/tsc.js
index 7f46b1dddb4..b1fac7955d0 100644
--- a/lib/tsc.js
+++ b/lib/tsc.js
@@ -67,7 +67,6 @@ var ts;
 (function (ts) {
     ts.timestamp = typeof performance !== "undefined" && performance.now ? function () { return performance.now(); } : Date.now ? Date.now : function () { return +(new Date()); };
 })(ts || (ts = {}));
-var ts;
 (function (ts) {
     var performance;
     (function (performance) {
@@ -7937,7 +7936,6 @@ var ts;
     }
     ts.isWatchSet = isWatchSet;
 })(ts || (ts = {}));
-var ts;
 (function (ts) {
     function getDefaultLibFileName(options) {
         return options.target === 2 ? "lib.es6.d.ts" : "lib.d.ts";