diff --git a/openerp/addons/base/ir/ir_http.py b/openerp/addons/base/ir/ir_http.py
index d8ece72e1b1..dde75a64a76 100644
--- a/openerp/addons/base/ir/ir_http.py
+++ b/openerp/addons/base/ir/ir_http.py
@@ -302,7 +302,7 @@ class ir_http(osv.AbstractModel):
 
         # cache
         etag = hasattr(request, 'httprequest') and request.httprequest.headers.get('If-None-Match')
-        retag = hashlib.md5(last_update).hexdigest()
+        retag = '"%s"' % hashlib.md5(last_update).hexdigest()
         status = status or (304 if etag == retag else 200)
         headers.append(('ETag', retag))
         headers.append(('Cache-Control', 'max-age=%s' % (STATIC_CACHE if unique else 0)))