diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 61fe2c7209a..80840068332 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -659,10 +659,6 @@ module ts {
         "\u0085": "\\u0085"  // nextLine
     };
 
-    export function getDefaultLibFileName(options: CompilerOptions): string {
-        return options.target === ScriptTarget.ES6 ? "lib.es6.d.ts" : "lib.d.ts";
-    }
-
     export interface ObjectAllocator {
         getNodeConstructor(kind: SyntaxKind): new () => Node;
         getSymbolConstructor(): new (flags: SymbolFlags, name: string) => Symbol;
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 46466478029..63eb3af784c 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -137,6 +137,10 @@ module ts {
         }
     }
 
+    export function getDefaultLibFileName(options: CompilerOptions): string {
+        return options.target === ScriptTarget.ES6 ? "lib.es6.d.ts" : "lib.d.ts";
+    }
+
     export function createProgram(rootNames: string[], options: CompilerOptions, host?: CompilerHost): Program {
         let program: Program;
         let files: SourceFile[] = [];