diff --git a/typescript-services/typescriptServices.d.ts b/typescript-services/typescriptServices.d.ts
index 18bef7b3d..25f174b43 100644
--- a/typescript-services/typescriptServices.d.ts
+++ b/typescript-services/typescriptServices.d.ts
@@ -5640,7 +5640,7 @@ declare module TypeScript {
         public hasBeenBound(): boolean;
         public isSynthesized(): boolean;
         public ast(): AST;
-        public isRootDecl(): void;
+        public isRootDecl(): boolean;
     }
     class RootPullDecl extends PullDecl {
         private _isExternalModule;
@@ -9317,4 +9317,4 @@ declare module TypeScript.Services {
 
 declare module 'typescript-services' {
     export = TypeScript;
-}
\ No newline at end of file
+}