diff --git a/cmd/mdio.c b/cmd/mdio.c
index cfa45ad..3c74326 100644
--- a/cmd/mdio.c
+++ b/cmd/mdio.c
@@ -254,7 +254,7 @@
 	switch (op[0]) {
 	case 'w':
 		if (pos > 1)
-			data = simple_strtoul(argv[pos--], NULL, 16);
+			data = hextoul(argv[pos--], NULL);
 		/* Intentional fall-through - Get reg for read and write */
 	case 'r':
 		if (pos > 1)