diff --git a/certbot/plugins/manual.py b/certbot/plugins/manual.py
index 98aa87cf2..1264e89c5 100644
--- a/certbot/plugins/manual.py
+++ b/certbot/plugins/manual.py
@@ -123,7 +123,7 @@ s.serve_forever()"
     def _perform_achall_with_script(self, achall, validation):
         env = dict(CERTBOT_DOMAIN=achall.domain, CERTBOT_VALIDATION=validation)
         if isinstance(achall.chall, challenges.HTTP01):
-            env['CERTBOT_TOKEN'] = achall.chall.encode("token")
+            env['CERTBOT_TOKEN'] = achall.chall.encode('token')
         os.environ.update(env)
         _, out = hooks.execute(self.conf('auth-script'))
         env['CERTBOT_AUTH_OUTPUT'] = out.strip()