diff --git a/src/ifcopenshell-python/ifcopenshell/api/cost/calculate_cost_item_resource_value.py b/src/ifcopenshell-python/ifcopenshell/api/cost/calculate_cost_item_resource_value.py
index 1d95942c0e..edac53057a 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/cost/calculate_cost_item_resource_value.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/cost/calculate_cost_item_resource_value.py
@@ -101,7 +101,7 @@ def calculate_cost_item_resource_value(file: ifcopenshell.file, cost_item: ifcop
 
     for resource in resources:
         cost, unit = ifcopenshell.util.resource.get_cost(resource)
-        if not cost:
+        if cost is None:
             # Concept to standardise - Not defined in schema, but this makes manual scheduling of resources 10x faster and less duplicate data.
             parent_cost = ifcopenshell.util.resource.get_parent_cost(resource)
             assert parent_cost