Use busybox error handling functions wherever possible.
diff --git a/sleep.c b/sleep.c
index ad92b10..10eca59 100644
--- a/sleep.c
+++ b/sleep.c
@@ -30,9 +30,7 @@
 		usage(sleep_usage);
 	}
 
-	if (sleep(atoi(*(++argv))) != 0) {
-		perror("sleep");
-		return EXIT_FAILURE;
-	}
+	if (sleep(atoi(*(++argv))) != 0)
+		perror_msg_and_die("sleep");
 	return EXIT_SUCCESS;
 }