diff --git a/move.py b/move.py
index 0b98e50909..23a3f6cd6a 100644
--- a/move.py
+++ b/move.py
@@ -454,8 +454,11 @@ class Line(ModelSQL, ModelView):
             select=1,
             on_change=['account', 'debit', 'credit', 'tax_lines',
                 'journal', 'move'])
-    move = fields.Many2One('account.move', 'Move', states=_LINE_STATES,
-            select=1, required=True)
+    move = fields.Many2One('account.move', 'Move', select=1, required=True,
+            states={
+                'required': False,
+                'readonly': Equal(Eval('state'), 'valid'),
+            })
     journal = fields.Function(fields.Many2One('account.journal', 'Journal'),
             'get_move_field', setter='set_move_field',
             searcher='search_move_field')
diff --git a/move.xml b/move.xml
index 8e5a61e055..6ed7a68ea0 100644
--- a/move.xml
+++ b/move.xml
@@ -220,7 +220,7 @@ this repository contains the full copyright notices and license terms. -->
                             <label name="maturity_date"/>
                             <field name="maturity_date"/>
                             <label name="move"/>
-                            <field name="move" required="0"/>
+                            <field name="move"/>
                             <label name="move_state"/>
                             <field name="move_state"/>
                             <label id="empty" colspan="2"/>
@@ -240,7 +240,7 @@ this repository contains the full copyright notices and license terms. -->
                 <tree string="Account Move Lines" editable="top"
                     on_write="on_write"
                     colors="If(Equal(Eval('state'), 'draft'), 'red', 'black')">
-                    <field name="move" select="1" required="0"/>
+                    <field name="move" select="1"/>
                     <field name="name" select="1"/>
                     <field name="reference" select="2"/>
                     <field name="date" select="1"/>
diff --git a/period.py b/period.py
index f9f4624eb9..cb73ea1719 100644
--- a/period.py
+++ b/period.py
@@ -29,7 +29,9 @@ class Period(ModelSQL, ModelView):
         ], 'State', readonly=True, required=True)
     post_move_sequence =fields.Many2One('ir.sequence', 'Post Move Sequence',
             required=True, domain=[('code', '=', 'account.move')],
-            context={'code': 'account.move'})
+            context={'code': 'account.move'}, states={
+            'required': False,
+            })
     type = fields.Selection([
         ('standard', 'Standard'),
         ('adjustment', 'Adjustment'),
diff --git a/period.xml b/period.xml
index 6c053dc8ca..7048aaa599 100644
--- a/period.xml
+++ b/period.xml
@@ -24,7 +24,7 @@ this repository contains the full copyright notices and license terms. -->
                     <field name="type"/>
                     <newline/>
                     <label name="post_move_sequence"/>
-                    <field name="post_move_sequence" required="0"/>
+                    <field name="post_move_sequence"/>
                     <newline/>
                     <label name="state"/>
                     <field name="state" colspan="3"/>