diff --git a/bom.py b/bom.py
index dc3faeb001..d4b631548e 100644
--- a/bom.py
+++ b/bom.py
@@ -28,6 +28,8 @@ class BOM(DeactivableMixin, ModelSQL, ModelView):
                 quantity = Uom.compute_qty(uom, quantity,
                     output.uom, round=False)
                 return quantity / output.quantity
+        else:
+            return 0.0
 
     @classmethod
     def copy(cls, records, default=None):