diff --git a/src/services/services.ts b/src/services/services.ts
index 41996349fba..a446c45aa8f 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -1878,7 +1878,7 @@ module ts {
                     newSourceFile.nameTable = undefined;
 
                     // dispose all resources held by old script snapshot
-                    if (sourceFile.scriptSnapshot) {
+                    if (sourceFile !== newSourceFile && sourceFile.scriptSnapshot) {
                         if (sourceFile.scriptSnapshot.dispose) {
                             sourceFile.scriptSnapshot.dispose();
                         }