diff --git a/sockjs/tornado/basehandler.py b/sockjs/tornado/basehandler.py
index <HASH>..<HASH> 100644
--- a/sockjs/tornado/basehandler.py
+++ b/sockjs/tornado/basehandler.py
@@ -116,11 +116,6 @@ class PreflightHandler(BaseHandler):
     def preflight(self):
         """Handles request authentication"""
         origin = self.request.headers.get('Origin', '*')
-
-        # Respond with '*' to 'null' origin
-        if origin == 'null':
-            origin = '*'
-
         self.set_header('Access-Control-Allow-Origin', origin)
 
         headers = self.request.headers.get('Access-Control-Request-Headers')
Do not reply with Allow-Origin '*' for null Origin

Otherwise local files do not work because of CORS issues, see <URL>