diff --git a/scripts/setup-seafile-mysql.py b/scripts/setup-seafile-mysql.py
index 9c5dcf0010..e7e9a66bb9 100644
--- a/scripts/setup-seafile-mysql.py
+++ b/scripts/setup-seafile-mysql.py
@@ -1056,7 +1056,7 @@ class SeahubConfigurator(AbstractConfigurator):
             script,
         ]
         key = Utils.get_command_output(cmd).strip()
-        fp.write('SECRET_KEY = "%s"' % key)
+        fp.write('SECRET_KEY = "%s"' % key.decode())
 
     def write_database_config(self, fp):
         template = '''\