diff --git a/src/bonsai/test/bim/test_feature.py b/src/bonsai/test/bim/test_feature.py
index 07d669aaa0..3bd861f31a 100644
--- a/src/bonsai/test/bim/test_feature.py
+++ b/src/bonsai/test/bim/test_feature.py
@@ -549,6 +549,8 @@ def i_set_the_prop_property_to_value(prop: str, value: str):
     """
     :param prop: Could be either property name, property text, property icon
         or property index (e.g. "1st", "2nd", "5th").
+    :param value:
+        For boolean propeties - 'TRUE' or 'FALSE'.
     """
     value = value.strip()
     assert panel_spy
@@ -566,6 +568,8 @@ def i_set_the_prop_property_to_value(prop: str, value: str):
                 setattr(spied_prop["props"], spied_prop["name"], True)
             elif value == "FALSE":
                 setattr(spied_prop["props"], spied_prop["name"], False)
+            else:
+                assert False, f"Unexpected value for BOOLEAN property: '{value}'. Allowed values: TRUE, FALSE."
         elif spied_prop["prop_type"] == "FLOAT":
             setattr(spied_prop["props"], spied_prop["name"], float(value))
         elif spied_prop["prop_type"] == "INT":