diff --git a/src/px4_connection/test/test_heartbeat_control_mode.py b/src/px4_connection/test/test_heartbeat_control_mode.py
index dff0e64f..72c6fe9a 100644
--- a/src/px4_connection/test/test_heartbeat_control_mode.py
+++ b/src/px4_connection/test/test_heartbeat_control_mode.py
@@ -28,7 +28,7 @@ def generate_test_description():
         }
     )
 
-class TestHeartbeatControlMode(unittest.TestCase)
+class TestHeartbeatControlMode(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):