diff --git a/openerp/osv/expression.py b/openerp/osv/expression.py
index 4715d9268c4..1e3ac1d0034 100644
--- a/openerp/osv/expression.py
+++ b/openerp/osv/expression.py
@@ -490,7 +490,7 @@ class ExtendedLeaf(object):
     #       i.e.: many2one: 'state_id': current field name
     # --------------------------------------------------
 
-    def __init__(self, leaf, model, join_context=None):
+    def __init__(self, leaf, model, join_context=None, internal=False):
         """ Initialize the ExtendedLeaf
 
             :attr [string, tuple] leaf: operator or tuple-formatted domain
@@ -529,7 +529,7 @@ class ExtendedLeaf(object):
             self._models.append(item[0])
         self._models.append(model)
         # check validity
-        self.check_leaf()
+        self.check_leaf(internal)
 
     def __str__(self):
         return '<osv.ExtendedLeaf: %s on %s (ctx: %s)>' % (str(self.leaf), self.model._table, ','.join(self._get_context_debug()))
@@ -575,7 +575,7 @@ class ExtendedLeaf(object):
     # Leaf manipulation
     # --------------------------------------------------
 
-    def check_leaf(self):
+    def check_leaf(self, internal=False):
         """ Leaf validity rules:
             - a valid leaf is an operator or a leaf
             - a valid leaf has a field objects unless
@@ -584,7 +584,7 @@ class ExtendedLeaf(object):
                 - left is id, operator is 'child_of'
                 - left is in MAGIC_COLUMNS
         """
-        if not is_operator(self.leaf) and not is_leaf(self.leaf, True):
+        if not is_operator(self.leaf) and not is_leaf(self.leaf, internal):
             raise ValueError("Invalid leaf %s" % str(self.leaf))
 
     def is_operator(self):
@@ -603,14 +603,14 @@ class ExtendedLeaf(object):
         self.leaf = normalize_leaf(self.leaf)
         return True
 
-def create_substitution_leaf(leaf, new_elements, new_model=None):
+def create_substitution_leaf(leaf, new_elements, new_model=None, internal=False):
     """ From a leaf, create a new leaf (based on the new_elements tuple
         and new_model), that will have the same join context. Used to
         insert equivalent leafs in the processing stack. """
     if new_model is None:
         new_model = leaf.model
     new_join_context = [tuple(context) for context in leaf.join_context]
-    new_leaf = ExtendedLeaf(new_elements, new_model, join_context=new_join_context)
+    new_leaf = ExtendedLeaf(new_elements, new_model, join_context=new_join_context, internal=internal)
     return new_leaf
 
 class expression(object):
@@ -1062,7 +1062,7 @@ class expression(object):
                         'model',
                         right,
                     )
-                    push(create_substitution_leaf(leaf, ('id', inselect_operator, (subselect, params)), working_model))
+                    push(create_substitution_leaf(leaf, ('id', inselect_operator, (subselect, params)), working_model, internal=True))
 
                 else:
                     push_result(leaf)