diff --git a/tests/web-server.py b/tests/web-server.py
index 4a2055f5..9dd82f17 100755
--- a/tests/web-server.py
+++ b/tests/web-server.py
@@ -37,6 +37,7 @@ class RequestHandler(http_server.SimpleHTTPRequestHandler):
     def do_GET(self):
         if self.handle_tokens():
             return None
+        self.headers.__delitem__("If-Modified-Since")
         return super().do_GET()
 
 def run(dir):