diff --git a/python/setup.py b/python/setup.py
index d003c969ab99..aab240a0e55a 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -207,7 +207,7 @@ def get_option_from_sys_argv(option_str):
     # C++ projects must now migrate to libc++ and are recommended to set a
     # deployment target of macOS 10.9 or later, or iOS 7 or later.
     if sys.platform == 'darwin':
-      mac_target = sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET')
+      mac_target = str(sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET'))
       if mac_target and (pkg_resources.parse_version(mac_target) <
                        pkg_resources.parse_version('10.9.0')):
         os.environ['MACOSX_DEPLOYMENT_TARGET'] = '10.9'