diff --git a/underscore.string/underscore.string.d.ts b/underscore.string/underscore.string.d.ts
index 9c828fdf7b..38271f3de5 100644
--- a/underscore.string/underscore.string.d.ts
+++ b/underscore.string/underscore.string.d.ts
@@ -3,6 +3,8 @@
 // Definitions by: Ry Racherbaumer <http://github.com/rygine>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
 
+/// <reference path="../underscore/underscore.d.ts" />
+
 interface UnderscoreStatic {
     str: UnderscoreStringStatic;
     string: UnderscoreStringStatic;