diff --git a/addons/mrp/mrp.py b/addons/mrp/mrp.py
index 038c608c26b..dfe45e927bc 100644
--- a/addons/mrp/mrp.py
+++ b/addons/mrp/mrp.py
@@ -324,10 +324,9 @@ class mrp_bom(osv.osv):
         """
         routing_obj = self.pool.get('mrp.routing')
         factor = factor / (bom.product_efficiency or 1.0)
-        max_rounding = max(bom.product_rounding, bom.product_uom.rounding)
-        factor = rounding(factor, max_rounding)
-        if factor < max_rounding:
-            factor = max_rounding
+        factor = rounding(factor, bom.product_rounding)
+        if factor < bom.product_rounding:
+            factor = bom.product_rounding
         result = []
         result2 = []
         phantom = False