diff --git a/master/buildbot/test/unit/scripts/test_copydb.py b/master/buildbot/test/unit/scripts/test_copydb.py
index 8b86b678e19..a26bdff0325 100644
--- a/master/buildbot/test/unit/scripts/test_copydb.py
+++ b/master/buildbot/test/unit/scripts/test_copydb.py
@@ -161,8 +161,8 @@ def resolve_db_url(self):
 
     def drop_database_tables(self, db_url):
         engine = enginestrategy.create_engine(db_url, basedir='basedir')
-        conn = engine.connect()
-        db.thd_clean_database(conn)
+        with engine.connect() as conn:
+            db.thd_clean_database(conn)
 
     @async_to_deferred
     async def test_full(self):