diff --git a/cmd/zip.c b/cmd/zip.c
index 8ad3768..08afd62 100644
--- a/cmd/zip.c
+++ b/cmd/zip.c
@@ -16,12 +16,12 @@
 
 	switch (argc) {
 		case 5:
-			dst_len = simple_strtoul(argv[4], NULL, 16);
+			dst_len = hextoul(argv[4], NULL);
 			/* fall through */
 		case 4:
-			src = simple_strtoul(argv[1], NULL, 16);
-			src_len = simple_strtoul(argv[2], NULL, 16);
-			dst = simple_strtoul(argv[3], NULL, 16);
+			src = hextoul(argv[1], NULL);
+			src_len = hextoul(argv[2], NULL);
+			dst = hextoul(argv[3], NULL);
 			break;
 		default:
 			return cmd_usage(cmdtp);