diff --git a/bin/addons/base/ir/ir_model.py b/bin/addons/base/ir/ir_model.py
index 105ffece9dc..7a020704110 100644
--- a/bin/addons/base/ir/ir_model.py
+++ b/bin/addons/base/ir/ir_model.py
@@ -244,13 +244,12 @@ class ir_model_fields(osv.osv):
             if not vals['name'].startswith('x_'):
                 raise except_orm(_('Error'), _("Custom fields must have a name that starts with 'x_' !"))
             
-            model_ids = self.pool.get('ir.model').search(cr, user, [('model','=',vals['relation'])])
-            if model_ids:
-                if self.pool.get(vals['model']):
-                    self.pool.get(vals['model']).__init__(self.pool, cr)
-                    self.pool.get(vals['model'])._auto_init(cr, {})
-            else:
-                raise except_orm(_('Error'), _("Model %s Does not Exist !" % vals['relation']))
+            if 'relation' in vals and not self.pool.get('ir.model').search(cr, user, [('model','=',vals['relation'])]):
+                 raise except_orm(_('Error'), _("Model %s Does not Exist !" % vals['relation']))
+
+            if self.pool.get(vals['model']):
+                self.pool.get(vals['model']).__init__(self.pool, cr)
+                self.pool.get(vals['model'])._auto_init(cr, {})
         return res
 ir_model_fields()