diff --git a/aider/prompts.py b/aider/prompts.py
index 84ed75e9b..aecf29a9e 100644
--- a/aider/prompts.py
+++ b/aider/prompts.py
@@ -13,11 +13,13 @@ Generate a one-line commit message for those changes.
 The commit message should be structured as follows: <type>: <description>
 Use these for <type>: fix, feat, build, chore, ci, docs, style, refactor, perf, test
 
-Ensure the commit message:
+Ensure the commit message:{language_instruction}
 - Starts with the appropriate prefix.
 - Is in the imperative mood (e.g., \"add feature\" not \"added feature\" or \"adding feature\").
 - Does not exceed 72 characters.
 
+Reply only with the one-line commit message, without any additional text, explanations, or line breaks.
+
 Reply only with the one-line commit message, without any additional text, explanations, \
 or line breaks.
 """
diff --git a/aider/repo.py b/aider/repo.py
index 0438f2243..809c8e375 100644
--- a/aider/repo.py
+++ b/aider/repo.py
@@ -207,7 +207,12 @@ class GitRepo:
         if message:
             commit_message = message
         else:
-            commit_message = self.get_commit_message(diffs, context)
+            user_language = None
+            if coder:
+                user_language = coder.get_user_language()
+            commit_message = self.get_commit_message(diffs, context, user_language)
+
+
 
         # Retrieve attribute settings, prioritizing coder.args if available
         if coder and hasattr(coder, "args"):
@@ -319,7 +324,7 @@ class GitRepo:
         except (ValueError, OSError):
             return self.repo.git_dir
 
-    def get_commit_message(self, diffs, context):
+    def get_commit_message(self, diffs, context, user_language=None):
         diffs = "# Diffs:\n" + diffs
 
         content = ""
@@ -328,6 +333,11 @@ class GitRepo:
         content += diffs
 
         system_content = self.commit_prompt or prompts.commit_system
+        language_instruction = ""
+        if user_language:
+            language_instruction = f"\n- Is written in {user_language}."
+        system_content = system_content.format(language_instruction=language_instruction)
+
         messages = [
             dict(role="system", content=system_content),
             dict(role="user", content=content),