diff --git a/examples/openapi3/reverseproxy/app.py b/examples/openapi3/reverseproxy/app.py
index 7974b647f..80fefbdca 100755
--- a/examples/openapi3/reverseproxy/app.py
+++ b/examples/openapi3/reverseproxy/app.py
@@ -42,7 +42,7 @@ def __init__(self, app, script_name=None, scheme=None, server=None):
     def __call__(self, environ, start_response):
         script_name = environ.get('HTTP_X_FORWARDED_PATH', '') or self.script_name
         if script_name:
-            environ['SCRIPT_NAME'] = script_name
+            environ['SCRIPT_NAME'] = "/" + script_name.lstrip("/")
             path_info = environ['PATH_INFO']
             if path_info.startswith(script_name):
                 environ['PATH_INFO_OLD'] = path_info