diff --git a/trytond/trytond/model/modelstorage.py b/trytond/trytond/model/modelstorage.py
index 27dbcef4bd..f0e6279315 100644
--- a/trytond/trytond/model/modelstorage.py
+++ b/trytond/trytond/model/modelstorage.py
@@ -1559,9 +1559,12 @@ class ModelStorage(Model):
                 vals[field] = []
                 for defaults2 in defaults[field]:
                     vals2 = obj._clean_defaults(defaults2)
-                    vals[field].append(('create', [vals2]))
+                    if vals2:
+                        vals[field].append(('create', [vals2]))
             elif fld_def._type in ('many2many',):
-                vals[field] = [('add', defaults[field])]
+                vals2 = defaults[field]
+                if vals2:
+                    vals[field] = [('add', vals2)]
             elif fld_def._type in ('boolean',):
                 vals[field] = bool(defaults[field])
             else: