diff --git a/fs/vboxsf/super.c b/fs/vboxsf/super.c
index 8fe03b4a0d2b..25aade344192 100644
--- a/fs/vboxsf/super.c
+++ b/fs/vboxsf/super.c
@@ -384,7 +384,7 @@ static int vboxsf_setup(void)
 
 static int vboxsf_parse_monolithic(struct fs_context *fc, void *data)
 {
-	char *options = data;
+	unsigned char *options = data;
 
 	if (options && options[0] == VBSF_MOUNT_SIGNATURE_BYTE_0 &&
 		       options[1] == VBSF_MOUNT_SIGNATURE_BYTE_1 &&