diff --git a/tests/Settings/TestContainerManager.py b/tests/Settings/TestContainerManager.py
index ff23b727e6..19ade68f68 100644
--- a/tests/Settings/TestContainerManager.py
+++ b/tests/Settings/TestContainerManager.py
@@ -14,6 +14,7 @@ class TestContainerManager(TestCase):
         self._application = MagicMock()
         self._container_registry = MagicMock()
         self._machine_manager = MagicMock()
+        self._machine_manager.activeMachine.extruderList = [MagicMock(name="Left Extruder Mock"), MagicMock(name="Right Extruder Mock")]
 
         self._mocked_mime = MagicMock()
         self._mocked_mime.preferredSuffix = "omg"