diff --git a/lumicks/pylake/tests/test_scalebar.py b/lumicks/pylake/tests/test_scalebar.py
index 650f1e157..3b356a352 100644
--- a/lumicks/pylake/tests/test_scalebar.py
+++ b/lumicks/pylake/tests/test_scalebar.py
@@ -1,5 +1,3 @@
-import json
-
 import numpy as np
 import pytest
 import matplotlib.pyplot as plt
@@ -25,7 +23,7 @@ def _validate_elements(ref_elements, item):
             else:
                 ref_elements.pop(idx)
         else:
-            raise AssertionError("Missing element")
+            raise AssertionError(f"Missing element {item}")
 
 
 @pytest.mark.parametrize(
@@ -35,32 +33,32 @@ def _validate_elements(ref_elements, item):
         # All entries
         (
             1, 2, "x", "y", "upper right", "white", 2, 2, 16,
-            ["Text(0, 0, 'y')", "Text(0, 0, 'x')", "Rectangle(xy=(0, 2), width=1, height=0, angle=0)", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)", "Text(0, 0, 'x')"]
+            ("Text(0, 0, 'y')", "Text(0, 0, 'x')", "Rectangle(xy=(0, 2), width=1, height=0, angle=0)", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)", "Text(0, 0, 'x')"),
         ),
         # No label for x
         (
             1, 2, None, "y", "upper right", "white", 2, 2, 16,
-            ["Text(0, 0, 'y')", "Rectangle(xy=(0, 2), width=1, height=0, angle=0)", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)"]
+            ("Text(0, 0, 'y')", "Rectangle(xy=(0, 2), width=1, height=0, angle=0)", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)"),
         ),
         # No label for y
         (
             1, 2, "x", None, "upper right", "white", 2, 2, 16,
-            ["Rectangle(xy=(0, 2), width=1, height=0, angle=0)", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)", "Text(0, 0, 'x')"]
+            ("Rectangle(xy=(0, 2), width=1, height=0, angle=0)", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)", "Text(0, 0, 'x')"),
         ),
         # No labels
         (
             1, 2, None, None, "upper right", "white", 2, 2, 16,
-            ["Rectangle(xy=(0, 2), width=1, height=0, angle=0)", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)"]
+            ("Rectangle(xy=(0, 2), width=1, height=0, angle=0)", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)"),
         ),
         # Only one axis
         (
             1, 0, "x", "y", "upper right", "white", 2, 2, 16,
-            ["Rectangle(xy=(0, 0), width=1, height=0, angle=0)", "Text(0, 0, 'x')"],
+            ("Rectangle(xy=(0, 0), width=1, height=0, angle=0)", "Text(0, 0, 'x')"),
         ),
         # Only one axis
         (
             0, 2, "x", "y", "upper right", "white", 2, 2, 16,
-            ["Text(0, 0, 'y')", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)"],
+            ("Text(0, 0, 'y')", "Rectangle(xy=(0, 0), width=0, height=2, angle=0)"),
         ),
         # fmt:on
     ],
@@ -75,9 +73,12 @@ def test_scalebar(
         axes.transData, size_x, size_y, label_x, label_y, loc, color, separation, barwidth, fontsize
     )
 
-    _validate_elements(reference, box)
-    if reference:
-        raise AssertionError(f"Not all elements were accounted for: {reference}")
+    # Note that _validate_elements pops items from this list (hence we copy to prevent mutating the
+    # input parametrization)
+    reference_list = list(reference)
+    _validate_elements(reference_list, box)
+    if reference_list:
+        raise AssertionError(f"Not all elements were accounted for: {reference_list}")
 
 
 def validate_args(refs):