diff --git a/src/compiler/tsc.ts b/src/compiler/tsc.ts
index a0d21106f43..0cbeff8204a 100644
--- a/src/compiler/tsc.ts
+++ b/src/compiler/tsc.ts
@@ -276,6 +276,7 @@ module ts {
 
         // If a source file changes, mark it as unwatched and start the recompilation timer
         function sourceFileChanged(sourceFile: SourceFile) {
+            sourceFile.fileWatcher.close();
             sourceFile.fileWatcher = undefined;
             startTimer();
         }