diff --git a/aider/coders/base_coder.py b/aider/coders/base_coder.py
index e8771118e..f63f5a599 100755
--- a/aider/coders/base_coder.py
+++ b/aider/coders/base_coder.py
@@ -479,7 +479,7 @@ class Coder:
 
         if edited:
             if self.repo and self.auto_commits and not self.dry_run:
-                saved_message = self.auto_commit(fnames=edited)
+                saved_message = self.auto_commit(edited)
             elif hasattr(self.gpt_prompts, "files_content_gpt_edits_no_repo"):
                 saved_message = self.gpt_prompts.files_content_gpt_edits_no_repo
             else:
diff --git a/aider/repo.py b/aider/repo.py
index ed25f462f..781d74441 100644
--- a/aider/repo.py
+++ b/aider/repo.py
@@ -56,7 +56,10 @@ class GitRepo:
         if message:
             commit_message = message
         else:
-            diffs = self.get_diffs(False)
+            diff_args = []
+            if fnames:
+                diff_args += ["--"] + list(fnames)
+            diffs = self.get_diffs(False, *diff_args)
             commit_message = self.get_commit_message(diffs, context)
 
         if not commit_message: