diff --git a/aider/args.py b/aider/args.py
index ba931f42d..6b97ea13f 100644
--- a/aider/args.py
+++ b/aider/args.py
@@ -136,7 +136,7 @@ def get_parser(default_config_files, git_root):
         help="Specify the OpenAI organization ID",
     )
     group.add_argument(
-        "--model_file",
+        "--model-file",
         metavar="MODEL_FILE",
         default=None,
         help={
diff --git a/aider/main.py b/aider/main.py
index 12ea6d6df..d177381f3 100644
--- a/aider/main.py
+++ b/aider/main.py
@@ -337,8 +337,8 @@ def main(argv=None, input=None, output=None, force_git_root=None, return_coder=F
     model_def_files.append(Path.home() / model_def_fname)  # homedir
     if git_root:
         model_def_files.append(Path(git_root) / model_def_fname)  # git root
-    if args.models:
-        model_def_files.append(args.models)
+    if args.model_file:
+        model_def_files.append(args.model_file)
     model_def_files = list(map(str, model_def_files))
     models.register_models(model_def_files)