diff --git a/awx/api/views/__init__.py b/awx/api/views/__init__.py
index 8a61c10ef6..2dfb35c462 100644
--- a/awx/api/views/__init__.py
+++ b/awx/api/views/__init__.py
@@ -181,7 +181,7 @@ def unpartitioned_event_horizon(cls):
     with connection.cursor() as cursor:
         try:
             cursor.execute(f'SELECT MAX(id) FROM _unpartitioned_{cls._meta.db_table}')
-            return cursor.fetchone()[0]
+            return cursor.fetchone()[0] or -1
         except ProgrammingError:
             return 0