diff --git a/CHANGES.rst b/CHANGES.rst
index c353bbb..e91dfd6 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -4,7 +4,7 @@ Changelog for Isso
 0.9.4 (unreleased)
 ------------------
 
-- Nothing changed yet.
+- fixed a regression when using Isso and Gevent
 
 
 0.9.3 (2014-07-09)
diff --git a/isso/wsgi.py b/isso/wsgi.py
index 37605c3..a2753f9 100644
--- a/isso/wsgi.py
+++ b/isso/wsgi.py
@@ -142,7 +142,7 @@ class CORSMiddleware(object):
             return start_response(status, headers.to_list(), exc_info)
 
         if environ.get("REQUEST_METHOD") == "OPTIONS":
-            add_cors_headers("200 Ok", [("Content-Type", "text/plain")])
+            add_cors_headers(b"200 Ok", [("Content-Type", "text/plain")])
             return [b'200 Ok']
 
         return self.app(environ, add_cors_headers)