diff --git a/tryton/wizard/main.py b/tryton/wizard/main.py
index 0c26c9751e..af9f1de502 100644
--- a/tryton/wizard/main.py
+++ b/tryton/wizard/main.py
@@ -121,7 +121,7 @@ class Wizard(object):
 
             if 'datas' in res:
                 datas['form'] = res['datas']
-            else:
+            elif res['type'] == 'form':
                 datas['form'] = {}
             if res['type'] == 'form':
                 if not dia: