diff --git a/plan.py b/plan.py
index 3063898..4724ffd 100644
--- a/plan.py
+++ b/plan.py
@@ -163,11 +163,16 @@ class Plan(ModelSQL, ModelView):
             return boms
 
         products = set(self.find_boms())
+        new_boms = set()
         for index, (product_id, _) in enumerate(products):
+            new_boms.add(product_id)
             boms['add'].append((index, {
                         'product': product_id,
                         'bom': None,
                         }))
+
+        if {x.product.id for x in self.boms if x.product} == new_boms:
+            return {}
         return boms
 
     def get_products_tree(self, name):