diff --git a/frontend/src/features/system/pages/CommonCodeManagementPage.vue b/frontend/src/features/system/pages/CommonCodeManagementPage.vue
index adcc9058..f9549c4c 100644
--- a/frontend/src/features/system/pages/CommonCodeManagementPage.vue
+++ b/frontend/src/features/system/pages/CommonCodeManagementPage.vue
@@ -239,7 +239,7 @@ const addGridRow = () => {
   let list = mockChildCodesMap[groupCodeKey]
   if (!list) {
     list = []
-    mockChildCodesMap[groupCodeKey] = list
+    Object.assign(mockChildCodesMap, { [groupCodeKey]: list })
   }
   const newRow: CommonCode = {
     code: `NEW_CODE_${list.length + 1}`,