diff --git a/src/rocker/cli.py b/src/rocker/cli.py
index 8bf2103..e55006f 100644
--- a/src/rocker/cli.py
+++ b/src/rocker/cli.py
@@ -33,7 +33,7 @@ def main():
         formatter_class=argparse.ArgumentDefaultsHelpFormatter)
     parser.add_argument('image')
     parser.add_argument('command', nargs='*', default='')
-    parser.add_argument('--config', help='Optional yaml file to handle command line arguments as a config file. This config will override any other command line arguments of the same name as the yaml keys')
+    parser.add_argument('--config', help='Optional yaml file to handle command line arguments (except positional args) as a config file. This config will override any other command line arguments of the same name as the yaml keys (e.g. "--user-override-name" would have the key "user_override_name" in the config file)')
     parser.add_argument('--noexecute', action='store_true', help='Deprecated')
     parser.add_argument('--nocache', action='store_true')
     parser.add_argument('--nocleanup', action='store_true', help='do not remove the docker container when stopped')