diff --git a/addons/product/product.py b/addons/product/product.py
index 49cd3b7fded..5e0abcc691a 100644
--- a/addons/product/product.py
+++ b/addons/product/product.py
@@ -660,7 +660,8 @@ class product_template(osv.osv):
                 for variant in all_variants:
                     for value_id in variant_id.value_ids:
                         temp_variants.append(variant + [int(value_id)])
-                all_variants = temp_variants
+                if temp_variants:
+                    all_variants = temp_variants
 
             # adding an attribute with only one value should not recreate product
             # write this attribute on every product to make sure we don't lose them