diff --git a/builtin-commit.c b/builtin-commit.c
index f37a90f..6c2dc39 100644
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -676,6 +676,14 @@
 	return git_status_config(k, v);
 }
 
+static int is_a_merge(const unsigned char *sha1)
+{
+	struct commit *commit = lookup_commit(sha1);
+	if (!commit || parse_commit(commit))
+		die("could not parse HEAD commit");
+	return !!(commit->parents && commit->parents->next);
+}
+
 static const char commit_utf8_warn[] =
 "Warning: commit message does not conform to UTF-8.\n"
 "You may want to amend it after fixing the message, or set the config\n"
@@ -701,7 +709,8 @@
 		return 1;
 	}
 
-	if (!prepare_log_message(index_file, prefix) && !in_merge) {
+	if (!prepare_log_message(index_file, prefix) && !in_merge &&
+	    !(amend && is_a_merge(head_sha1))) {
 		run_status(stdout, index_file, prefix);
 		rollback_index_files();
 		unlink(commit_editmsg);