diff --git a/nion/instrumentation/test/CameraControl_test.py b/nion/instrumentation/test/CameraControl_test.py
index <HASH>..<HASH> 100644
--- a/nion/instrumentation/test/CameraControl_test.py
+++ b/nion/instrumentation/test/CameraControl_test.py
@@ -38,6 +38,7 @@ class TestCameraControlClass(unittest.TestCase):
 
     def tearDown(self):
         HardwareSource.HardwareSourceManager()._close_hardware_sources()
+        HardwareSource.HardwareSourceManager()._close_instruments()
 
     def _acquire_one(self, document_controller, hardware_source):
         hardware_source.start_playing()
diff --git a/nion/instrumentation/test/ScanControl_test.py b/nion/instrumentation/test/ScanControl_test.py
index <HASH>..<HASH> 100644
--- a/nion/instrumentation/test/ScanControl_test.py
+++ b/nion/instrumentation/test/ScanControl_test.py
@@ -38,6 +38,7 @@ class TestScanControlClass(unittest.TestCase):
 
     def tearDown(self):
         HardwareSource.HardwareSourceManager()._close_hardware_sources()
+        HardwareSource.HardwareSourceManager()._close_instruments()
 
     def _acquire_one(self, document_controller, hardware_source):
         hardware_source.start_playing(3.0)
Ensure proper instrument shutdowns (was causing failing tests).