diff --git a/odoo/addons/base/models/ir_http.py b/odoo/addons/base/models/ir_http.py
index 5418789b716..70730917ae2 100644
--- a/odoo/addons/base/models/ir_http.py
+++ b/odoo/addons/base/models/ir_http.py
@@ -82,6 +82,9 @@ class IrHttp(models.AbstractModel):
     # Routing map
     #------------------------------------------------------
 
+    _routing_map = {}
+    _rewrite_len = {}
+
     @classmethod
     def _get_converters(cls):
         return {'model': ModelConverter, 'models': ModelsConverter, 'int': SignedIntConverter}
@@ -250,9 +253,6 @@ class IrHttp(models.AbstractModel):
 
     @classmethod
     def routing_map(cls, key=None):
-        if not hasattr(cls, '_routing_map'):
-            cls._routing_map = {}
-            cls._rewrite_len = {}
         if key not in cls._routing_map:
             _logger.info("Generating routing map for key %s" % str(key))
             installed = request.registry._init_modules | set(odoo.conf.server_wide_modules)