diff --git a/src/ifcopenshell-python/ifcopenshell/express/rule_executor.py b/src/ifcopenshell-python/ifcopenshell/express/rule_executor.py
index e9b66a56fb..9ba2a592e8 100644
--- a/src/ifcopenshell-python/ifcopenshell/express/rule_executor.py
+++ b/src/ifcopenshell-python/ifcopenshell/express/rule_executor.py
@@ -197,10 +197,14 @@ def run(f, logger):
             type = type.declared_type()
 
         if isinstance(value, (list, tuple)):
-            assert isinstance(type, ifcopenshell.ifcopenshell_wrapper.aggregation_type)
-            ty = type.type_of_element()
-            for v in value:
-                check(v, ty, instance=inst)
+            if isinstance(type, ifcopenshell.ifcopenshell_wrapper.aggregation_type):
+                ty = type.type_of_element()
+                for v in value:
+                    check(v, ty, instance=inst)
+            else:
+                # Let's hope a schema validation error was reported for this case
+                pass
+
         elif isinstance(value, ifcopenshell.entity_instance):
             if isinstance(
                 S.declaration_by_name(value.is_a()),