diff --git a/src/core/controller_utils.py b/src/core/controller_utils.py
index a0d801a..3dfe3f5 100644
--- a/src/core/controller_utils.py
+++ b/src/core/controller_utils.py
@@ -655,7 +655,7 @@ def Helper__DeleteFileIntoIndex(
             if len(indexItemData) == 0:  # it is an abnormal situation
                 filesByStrKeyDictionary.pop(fileKey)
             elif len(indexItemData) == 1:
-                filesByStrKeyDictionary[fileKey] == indexItemData[0]
+                filesByStrKeyDictionary[fileKey] = indexItemData[0]
 
             return