diff --git a/flaskext/sqlalchemy.py b/flaskext/sqlalchemy.py
index a4ede2a6..a0f2178f 100644
--- a/flaskext/sqlalchemy.py
+++ b/flaskext/sqlalchemy.py
@@ -593,7 +593,8 @@ class User(db.Model):
     """
 
     def __init__(self, app=None, use_native_unicode=True,
-                 session_extensions=None, session_options=None):
+                 session_extensions=None, session_options=None,
+                 metaclass=None):
         self.use_native_unicode = use_native_unicode
         self.session_extensions = to_list(session_extensions, []) + \
                                   [_SignallingSessionExtension()]
@@ -606,6 +607,7 @@ def __init__(self, app=None, use_native_unicode=True,
         )
 
         self.session = self.create_scoped_session(session_options)
+        self.metaclass = metaclass if metaclass else _BoundDeclarativeMeta
         self.Model = self.make_declarative_base()
         self._engine_lock = Lock()
 
@@ -636,7 +638,7 @@ def make_declarative_base(self):
         """Creates the declarative base."""
         base = declarative_base(cls=Model, name='Model',
                                 mapper=signalling_mapper,
-                                metaclass=_BoundDeclarativeMeta)
+                                metaclass=self.metaclass)
         base.query = _QueryProperty(self)
         return base