diff --git a/rclpy/test/test_client.py b/rclpy/test/test_client.py
index 6903fc78b..a4513c511 100644
--- a/rclpy/test/test_client.py
+++ b/rclpy/test/test_client.py
@@ -105,7 +105,7 @@ def test_service_timestamps(self):
             for i in range(5):
                 with srv.handle:
                     result = srv.handle.service_take_request(srv.srv_type.Request)
-                if result is not None:
+                if result != (None, None):
                     request, header = result
                     self.assertTrue(header is not None)
                     self.assertNotEqual(0, header.source_timestamp)