diff --git a/mailmap.c b/mailmap.c
index 2d0212f444..2acf97f307 100644
--- a/mailmap.c
+++ b/mailmap.c
@@ -201,8 +201,10 @@ static int read_mailmap_blob(struct string_list *map, const char *name)
 	buf = repo_read_object_file(the_repository, &oid, &type, &size);
 	if (!buf)
 		return error("unable to read mailmap object at %s", name);
-	if (type != OBJ_BLOB)
+	if (type != OBJ_BLOB) {
+		free(buf);
 		return error("mailmap is not a blob: %s", name);
+	}
 
 	read_mailmap_string(map, buf);
 
diff --git a/t/t4203-mailmap.sh b/t/t4203-mailmap.sh
index 8a88dd7900..79e5f42760 100755
--- a/t/t4203-mailmap.sh
+++ b/t/t4203-mailmap.sh
@@ -5,6 +5,7 @@ test_description='.mailmap configurations'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 test_expect_success 'setup commits and contacts file' '