diff --git a/picamera_coverage.zip b/picamera_coverage.zip
index 09438bb3..f971f063 100644
Binary files a/picamera_coverage.zip and b/picamera_coverage.zip differ
diff --git a/src/openflexure_microscope_server/things/camera/picamera_recalibrate_utils.py b/src/openflexure_microscope_server/things/camera/picamera_recalibrate_utils.py
index 1ce49f86..1c00f63f 100644
--- a/src/openflexure_microscope_server/things/camera/picamera_recalibrate_utils.py
+++ b/src/openflexure_microscope_server/things/camera/picamera_recalibrate_utils.py
@@ -243,7 +243,7 @@ def _set_minimum_exposure(camera: Picamera2, sensor_info: SensorInfo) -> None:
     time.sleep(sensor_info.long_pause)
     # Flush stale frames
     for _ in range(2):
-        r = camera.capture_metadata()
+        _r = camera.capture_metadata()
 
 
 def _test_exposure_settings(camera: Picamera2, percentile: float) -> _ExposureTest: