diff --git a/source-map/source-map-tests.ts b/source-map/source-map-tests.ts
index f7ad78e85..3ec6b666d 100644
--- a/source-map/source-map-tests.ts
+++ b/source-map/source-map-tests.ts
@@ -1,3 +1,5 @@
+/// <reference path="./source-map.d.ts" />
+
 import SourceMap = require('source-map');
 
 function testSourceMapConsumer() {
@@ -162,4 +164,4 @@ function testSourceNode() {
         result = node.toStringWithSourceMap();
         result = node.toStringWithSourceMap(sos);
     }
-}
\ No newline at end of file
+}