diff --git a/src/openflexure_microscope_server/things/smart_scan.py b/src/openflexure_microscope_server/things/smart_scan.py
index a6da0b51..5e065b32 100644
--- a/src/openflexure_microscope_server/things/smart_scan.py
+++ b/src/openflexure_microscope_server/things/smart_scan.py
@@ -351,10 +351,16 @@ class SmartScanThing(OFMThing):
         finally:
             # Save some final details but not set to the base model until after
             # resetting valued and unlocking just in case somehow pydantic errors.
-            if self._scan_data is not None:
-                final_image_count = self._scan_data.image_count
-            if self._preview_stitcher is not None:
-                last_timestamp = self.latest_preview_stitch_time
+
+            final_image_count = (
+                self._scan_data.image_count if self._scan_data is not None else None
+            )
+            last_timestamp = (
+                self.latest_preview_stitch_time
+                if self._preview_stitcher is not None
+                else None
+            )
+
             # However the scan finishes, unset all variables and release lock
             self._ongoing_scan = None
             self._scan_data = None
@@ -364,8 +370,10 @@ class SmartScanThing(OFMThing):
 
             # Set the final details so they persist until the next scan
             if self._latest_scan_live_details is not None:
-                self._latest_scan_live_details.image_count = final_image_count
-                self._latest_scan_live_details.stitch_timestamp = last_timestamp
+                if final_image_count is not None:
+                    self._latest_scan_live_details.image_count = final_image_count
+                if last_timestamp is not None:
+                    self._latest_scan_live_details.stitch_timestamp = last_timestamp
                 self._latest_scan_live_details.scan_phase = "Complete"
 
             # Remove any scan folders containing zero images.
diff --git a/tests/unit_tests/test_smart_scan.py b/tests/unit_tests/test_smart_scan.py
index 481091fb..545d23d1 100644
--- a/tests/unit_tests/test_smart_scan.py
+++ b/tests/unit_tests/test_smart_scan.py
@@ -559,7 +559,7 @@ def test_run_scan_cancelled(scan_thing_mocked_for_run_scan, caplog, mocker):
         scan_thing, "_main_scan_loop", side_effect=InvocationCancelledError()
     )
 
-    result, logs, calls = check_run_scan(scan_thing, caplog)
+    result, logs, calls = check_run_scan(scan_thing, caplog, InvocationCancelledError)
 
     assert result == "cancelled by user"
     # No logs at warning level.
@@ -571,7 +571,7 @@ def test_run_scan_cancelled(scan_thing_mocked_for_run_scan, caplog, mocker):
         "cam_change_streaming_mode_calls": 2,
         "main_scan_loop_calls": 1,
         "return_to_start_calls": 1,
-        "perform_final_stitch_calls": 1,
+        "perform_final_stitch_calls": 0,
         "save_scan_data_calls": 2,
     }
     assert calls == expected_calls_numbers