diff --git a/os/src/main.rs b/os/src/main.rs
index 6baf556f..0f8784b8 100644
--- a/os/src/main.rs
+++ b/os/src/main.rs
@@ -1,9 +1,9 @@
 #![no_std]
 #![no_main]
-#![feature(global_asm)]
-#![feature(asm)]
 #![feature(panic_info_message)]
 
+use core::arch::global_asm;
+
 #[macro_use]
 mod console;
 mod lang_items;
diff --git a/os/src/sbi.rs b/os/src/sbi.rs
index a2970f8a..90ba2c2a 100644
--- a/os/src/sbi.rs
+++ b/os/src/sbi.rs
@@ -1,5 +1,7 @@
 #![allow(unused)]
 
+use core::arch::asm;
+
 const SBI_SET_TIMER: usize = 0;
 const SBI_CONSOLE_PUTCHAR: usize = 1;
 const SBI_CONSOLE_GETCHAR: usize = 2;
diff --git a/rust-toolchain b/rust-toolchain
index c9f86822..a8a61591 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1 +1 @@
-nightly-2021-12-15
+nightly-2022-01-01