diff --git a/trytond/model/modelview.py b/trytond/model/modelview.py
index a92c6ef9f3..2c8949b6e0 100644
--- a/trytond/model/modelview.py
+++ b/trytond/model/modelview.py
@@ -738,6 +738,7 @@ class ModelView(Model):
                     del value['remove']
                 if not value:
                     continue
+                value = dict(value)
             elif field._type == 'many2many':
                 value = [r.id for r in value]
             changed[fname] = value