diff --git a/odoo/service/server.py b/odoo/service/server.py
index 10c9cdb056d..ed5c1d96af8 100644
--- a/odoo/service/server.py
+++ b/odoo/service/server.py
@@ -126,19 +126,16 @@ class RequestHandler(werkzeug.serving.WSGIRequestHandler):
         me = threading.current_thread()
         me.name = 'odoo.service.http.request.%s' % (me.ident,)
 
-    def send_response(self, code, message=None):
-        # Since the upgrade header is introduced in version 1.1, Firefox
-        # won't accept a websocket connection if the version is set to
-        # 1.0.
-        if self.environ.get('REQUEST_URI') == '/websocket':
-            self.protocol_version = "HTTP/1.1"
-        return super().send_response(code, message=message)
-
     def make_environ(self):
         environ = super().make_environ()
         # Add the TCP socket to environ in order for the websocket
         # connections to use it.
         environ['socket'] = self.connection
+        if self.headers.get('Upgrade') == 'websocket':
+            # Since the upgrade header is introduced in version 1.1, Firefox
+            # won't accept a websocket connection if the version is set to
+            # 1.0.
+            self.protocol_version = "HTTP/1.1"
         return environ