diff --git a/apps/api/src/services/platform_operator_service.py b/apps/api/src/services/platform_operator_service.py
index b4f08414..7e04787b 100644
--- a/apps/api/src/services/platform_operator_service.py
+++ b/apps/api/src/services/platform_operator_service.py
@@ -277,13 +277,14 @@ async def list_callback_replies(
 
     where_clauses = [
         "m.source_envelope ? 'callback_reply'",
-        "(:project_id IS NULL OR m.project_id = :project_id)",
     ]
     params: dict[str, Any] = {
-        "project_id": project_id,
         "limit": per_page,
         "offset": (page - 1) * per_page,
     }
+    if project_id:
+        where_clauses.append("m.project_id = :project_id")
+        params["project_id"] = project_id
 
     raw_status = _CALLBACK_REPLY_RAW_STATUS_BY_FILTER.get(
         str(callback_reply_status or "")