diff --git a/dox/config/dox_yaml.py b/dox/config/dox_yaml.py
index 20dfbb6..5a2097a 100644
--- a/dox/config/dox_yaml.py
+++ b/dox/config/dox_yaml.py
@@ -47,7 +47,7 @@ class DoxYaml(object):
         return self._open_dox_yaml().get('image', image)
 
     def get_commands(self, extra_args):
-        return self._open_dox_yaml().get('commands') + " ".join(extra_args)
+        return " ".join([self._open_dox_yaml().get('commands')] +extra_args)
 
     def get_prep_commands(self):
         return self._open_dox_yaml().get('prep')