diff --git a/tools/testing/selftests/watchdog/watchdog-test.c b/tools/testing/selftests/watchdog/watchdog-test.c
index e7c9d3bdae5661e3cae64d2e7bcd4882cac33dcb..5cfa88c7309517f306fefe547288934236bdad59 100644
--- a/tools/testing/selftests/watchdog/watchdog-test.c
+++ b/tools/testing/selftests/watchdog/watchdog-test.c
@@ -106,7 +106,7 @@ int main(int argc, char *argv[])
 			printf("Watchdog ping rate set to %u seconds.\n", ping_rate);
 			break;
 		case 't':
-			flags = atoi(optarg);
+			flags = strtoul(optarg, NULL, 0);
 			ret = ioctl(fd, WDIOC_SETTIMEOUT, &flags);
 			if (!ret)
 				printf("Watchdog timeout set to %u seconds.\n", flags);