diff --git a/tobiko/common/utils/network.py b/tobiko/common/utils/network.py
index b97f4e8df..f7c278525 100644
--- a/tobiko/common/utils/network.py
+++ b/tobiko/common/utils/network.py
@@ -25,8 +25,8 @@ from tempest.lib.common.utils import test_utils
 
 from tobiko import config
 
-SHELL = config.get_any_option('tobiko.shell.command',
-                              default='bin/sh -c').split()
+SHELL = (config.get_any_option('tobiko.shell.command') or
+         'bin/sh -c').split()
 
 
 SG_RULES = {'ALLOW_ICMP':