diff --git a/src/openflexure_microscope_server/scan_planners.py b/src/openflexure_microscope_server/scan_planners.py
index 11ea5abf..3a215183 100644
--- a/src/openflexure_microscope_server/scan_planners.py
+++ b/src/openflexure_microscope_server/scan_planners.py
@@ -504,7 +504,7 @@ class SmartSpiral(ScanPlanner):
         """Sort the remaining positions based on the current location."""
 
         # Defined rather than use a lambda for readability
-        def sort_key(pos: FutureScanLocation) -> tuple[float, float, float]:
+        def sort_key(pos: FutureScanLocation) -> tuple[bool, float, float, float]:
             return (
                 self._is_primary_location(pos),  # False sorts low
                 self.moves_between(current_pos, pos),
diff --git a/tests/utilities/scan_test_helpers.py b/tests/utilities/scan_test_helpers.py
index aa45f442..bf22876a 100755
--- a/tests/utilities/scan_test_helpers.py
+++ b/tests/utilities/scan_test_helpers.py
@@ -67,7 +67,10 @@ def visualise_scan(sample: FakeSample, planner: scan_planners.ScanPlanner) -> Fi
     ax.add_artist(sample.patch)
     xh, yh = zip(*planner.path_history, strict=True)
     xi, yi, _zi = zip(*planner.imaged_locations, strict=True)
-    xs, ys, _zs = zip(*planner.secondary_locations, strict=True)
+    if planner.secondary_locations:
+        xs, ys, _zs = zip(*planner.secondary_locations, strict=True)
+    else:
+        xs, ys, _zs = [], [], []
 
     # convert history to numpy array so can calculate quiver arrows
     xh = np.array(xh)