diff --git a/lib/link/seven_fs/open_file.c b/lib/link/seven_fs/open_file.c
index 3ec4297..6213f11 100644
--- a/lib/link/seven_fs/open_file.c
+++ b/lib/link/seven_fs/open_file.c
@@ -185,9 +185,9 @@ int CASIO_EXPORT casio_sevenfs_open(sevenfs_cookie_t *cookie, sevenfs_path_t *pa
 		casio_off_t size, casio_openmode_t mode, casio_stream_t **stream)
 {
 	casio_link_t *handle = cookie; int err;
-	char *dirname = &path->sevenfs_path_data[path->sevenfs_path_dir];
-	char *filename = &path->sevenfs_path_data[path->sevenfs_path_file];
-	char *devname = &path->sevenfs_path_data[path->sevenfs_path_dev];
+	const char *dirname = &path->sevenfs_path_data[path->sevenfs_path_dir];
+	const char *filename = &path->sevenfs_path_data[path->sevenfs_path_file];
+	const char *devname = &path->sevenfs_path_data[path->sevenfs_path_dev];
 
 	/* Make checks (not really required) */
 	chk_required_filename(filename);