diff --git a/src/flask_session/postgresql/postgresql.py b/src/flask_session/postgresql/postgresql.py
index b5f1e8d6..9ad198bb 100644
--- a/src/flask_session/postgresql/postgresql.py
+++ b/src/flask_session/postgresql/postgresql.py
@@ -140,6 +140,6 @@ def _upsert_session(
                 ),
             )
 
-    def _drop_table(self):
+    def _drop_table(self) -> None:
         with self._get_cursor() as cur:
             cur.execute(self._queries.drop_sessions_table)