diff --git a/src/openflexure_microscope_server/things/camera/__init__.py b/src/openflexure_microscope_server/things/camera/__init__.py
index b43b8dd9..049f2a29 100644
--- a/src/openflexure_microscope_server/things/camera/__init__.py
+++ b/src/openflexure_microscope_server/things/camera/__init__.py
@@ -323,14 +323,14 @@ class BaseCamera(OFMThing):
         os.makedirs(output_dir, exist_ok=True)
 
         timestamp = time.strftime("%Y%m%d_%H%M%S")
-        log_path = os.path.join(
+        datafile_path = os.path.join(
             output_dir,
             f"framerate_{timestamp}.json",
         )
 
         self.logger.info(
             "Framerate monitor started -> %s",
-            log_path,
+            datafile_path,
         )
 
         self._framerate_monitor_running = True
@@ -363,15 +363,15 @@ class BaseCamera(OFMThing):
             avg_fps,
         )
 
-        with open(log_path, "w") as f:
+        with open(datafile_path, "w") as f:
             json.dump(data, f, indent=2)
 
         self.logger.info(
             "Framerate monitor complete -> %s",
-            log_path,
+            datafile_path,
         )
 
-        return log_path
+        return datafile_path
 
     @lt.property
     def stream_active(self) -> bool:
diff --git a/src/openflexure_microscope_server/things/camera/picamera.py b/src/openflexure_microscope_server/things/camera/picamera.py
index 93f536fa..b76d4ed5 100644
--- a/src/openflexure_microscope_server/things/camera/picamera.py
+++ b/src/openflexure_microscope_server/things/camera/picamera.py
@@ -167,7 +167,6 @@ class StreamingPiCamera2(BaseCamera):
         self._sensor_info = SUPPORTED_CAMS_SENSOR_INFO[camera_board]
         self._picamera_lock = RLock()
         self._picamera = None
-        self._framerate_monitor_running = False
 
         # Load the tuning file for the specified sensor mode.
         self.default_tuning = tf_utils.load_default_tuning(
diff --git a/tests/shared_utils/lt_test_utils.py b/tests/shared_utils/lt_test_utils.py
index 19b61723..6e272c1d 100644
--- a/tests/shared_utils/lt_test_utils.py
+++ b/tests/shared_utils/lt_test_utils.py
@@ -48,7 +48,11 @@ class LabThingsTestEnv:
         self._test_client: Optional[TestClient]
         self._things_config = things
         self._settings_folder = settings_folder
-        self._application_config = application_config
+        # Labthings requires an application config for the data_folder
+        if application_config:
+            self._application_config = application_config
+        else:
+            self._application_config = {"data_folder": tempfile.TemporaryDirectory()}
         self._tmp_dir_obj: Optional[tempfile.TemporaryDirectory] = None
 
     def __enter__(self) -> Self:
diff --git a/tests/unit_tests/test_base_camera.py b/tests/unit_tests/test_base_camera.py
index c8b64274..aba5b4ea 100644
--- a/tests/unit_tests/test_base_camera.py
+++ b/tests/unit_tests/test_base_camera.py
@@ -5,8 +5,6 @@ test_simulated_camera.py and for testing the consistency of camera APIs see
 test_cameras.py.
 """
 
-import tempfile
-
 import numpy as np
 import pytest
 from PIL import Image
@@ -21,8 +19,7 @@ from ..shared_utils.lt_test_utils import LabThingsTestEnv
 def test_env() -> LabThingsTestEnv:
     """Yield a test environment with the Simulated Camera and Dummy Stage."""
     thing_conf = {"camera": SimulatedCamera, "stage": DummyStage}
-    app_config = {"data_folder": tempfile.gettempdir()}
-    with LabThingsTestEnv(things=thing_conf, application_config=app_config) as env:
+    with LabThingsTestEnv(things=thing_conf) as env:
         yield env
 
 
diff --git a/tests/unit_tests/test_metadata.py b/tests/unit_tests/test_metadata.py
index 4b158e5a..7c5f87b6 100644
--- a/tests/unit_tests/test_metadata.py
+++ b/tests/unit_tests/test_metadata.py
@@ -1,7 +1,6 @@
 """Tests that captures have the expected metadata."""
 
 import json
-import tempfile
 from datetime import datetime
 from pathlib import Path
 
@@ -100,8 +99,7 @@ def test_env() -> LabThingsTestEnv:
         "stage": DummyStage,
         "bg_channel_deviations_luv": ChannelDeviationLUV,
     }
-    app_config = {"data_folder": tempfile.gettempdir()}
-    with LabThingsTestEnv(things=thing_conf, application_config=app_config) as env:
+    with LabThingsTestEnv(things=thing_conf) as env:
         yield env
 
 
diff --git a/tests/unit_tests/test_simulated_camera.py b/tests/unit_tests/test_simulated_camera.py
index 8b76106c..99f486be 100644
--- a/tests/unit_tests/test_simulated_camera.py
+++ b/tests/unit_tests/test_simulated_camera.py
@@ -1,7 +1,6 @@
 """Test the functionality specific to the simulated camera."""
 
 import logging
-import tempfile
 import time
 
 import numpy as np
@@ -29,9 +28,7 @@ def test_env() -> LabThingsTestEnv:
         "bg_channel_deviations_luv": ChannelDeviationLUV,
     }
 
-    app_config = {"data_folder": tempfile.gettempdir()}
-
-    with LabThingsTestEnv(things=thing_conf, application_config=app_config) as env:
+    with LabThingsTestEnv(things=thing_conf) as env:
         yield env
 
 
diff --git a/tests/unit_tests/test_stage.py b/tests/unit_tests/test_stage.py
index a699b65f..f922ef65 100644
--- a/tests/unit_tests/test_stage.py
+++ b/tests/unit_tests/test_stage.py
@@ -2,7 +2,6 @@
 
 import itertools
 import logging
-import tempfile
 import threading
 import time
 from dataclasses import dataclass
@@ -177,8 +176,7 @@ def test_direction_inversion(dummy_stage):
 def test_direction_errors_local_and_http():
     """Check for expected errors both locally and over http."""
     thing_conf = {"camera": SimulatedCamera, "stage": DummyStage}
-    app_config = {"data_folder": tempfile.gettempdir()}
-    with LabThingsTestEnv(things=thing_conf, application_config=app_config) as test_env:
+    with LabThingsTestEnv(things=thing_conf) as test_env:
         dummy_stage = test_env.get_thing_by_type(DummyStage)
         stage_client = test_env.get_thing_client("stage")