diff --git a/services/core.py b/services/core.py
index fdcefea..076b929 100644
--- a/services/core.py
+++ b/services/core.py
@@ -65,7 +65,7 @@ async def get_my_followed() -> List[ChatMember]:
 async def get_author(user: str = ""):
     query_name = "get_author_id(user: $user)"
     query_type = "query"
-    operation = "GetAuthor($user: String)"
+    operation = "GetAuthor($user: String!)"
     query_fields = "id slug pic name"
 
     gql = {