diff --git a/openerp/models.py b/openerp/models.py
index 14692869c14..eddef09cd31 100644
--- a/openerp/models.py
+++ b/openerp/models.py
@@ -2767,8 +2767,8 @@ class BaseModel(object):
             if not cr.fetchall():
                 self._m2o_add_foreign_key_unchecked(m2m_tbl, col1, self, 'cascade')
 
-            cr.execute('CREATE INDEX "%s_%s_index" ON "%s" ("%s")' % (m2m_tbl, col1, m2m_tbl, col1))
-            cr.execute('CREATE INDEX "%s_%s_index" ON "%s" ("%s")' % (m2m_tbl, col2, m2m_tbl, col2))
+            cr.execute('CREATE INDEX ON "%s" ("%s")' % (m2m_tbl, col1))
+            cr.execute('CREATE INDEX ON "%s" ("%s")' % (m2m_tbl, col2))
             cr.execute("COMMENT ON TABLE \"%s\" IS 'RELATION BETWEEN %s AND %s'" % (m2m_tbl, self._table, ref))
             cr.commit()
             _schema.debug("Create table '%s': m2m relation between '%s' and '%s'", m2m_tbl, self._table, ref)