diff --git a/sqlite_utils/db.py b/sqlite_utils/db.py
index bc65f2f5..2be7a6d4 100644
--- a/sqlite_utils/db.py
+++ b/sqlite_utils/db.py
@@ -369,7 +369,7 @@ def __init__(
             pm.hook.prepare_connection(conn=self.conn)
         self.strict = strict
 
-    def close(self):
+    def close(self) -> None:
         "Close the SQLite connection, and the underlying database file"
         self.conn.close()