diff --git a/src/services/services.ts b/src/services/services.ts
index 41ffc04e5ae..fa419cf9f10 100644
--- a/src/services/services.ts
+++ b/src/services/services.ts
@@ -3641,8 +3641,24 @@ module ts {
             }
         }
 
-        /// References and Occurrences
         function getOccurrencesAtPosition(fileName: string, position: number): ReferenceEntry[] {
+            let results = getOccurrencesAtPositionCore(fileName, position);
+            
+            if (results) {
+                let sourceFile = getCanonicalFileName(normalizeSlashes(fileName));
+
+                // ensure the results are in the file we're interested in
+                results.forEach((value) => {
+                    let targetFile = getCanonicalFileName(normalizeSlashes(value.fileName));
+                    Debug.assert(sourceFile == targetFile, `Unexpected file in results. Found results in ${targetFile} expected only results in ${sourceFile}.`);
+                });
+            }
+
+            return results;
+        }
+
+        /// References and Occurrences
+        function getOccurrencesAtPositionCore(fileName: string, position: number): ReferenceEntry[] {
             synchronizeHostData();
 
             let sourceFile = getValidSourceFile(fileName);