diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6aba1f2..0e2cc73 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -43,7 +43,8 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: nightly
+          # asm! is stable and llvm_asm! still exists
+          toolchain: nightly-2022-01-14
           target: ${{ matrix.target }}
           override: true
 
diff --git a/src/lib.rs b/src/lib.rs
index 59f45e6..a30fe48 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -11,8 +11,18 @@
 
 // Reference http://man7.org/linux/man-pages/man2/syscall.2.html
 
+#![allow(deprecated)] // llvm_asm!
 #![deny(warnings)]
 #![no_std]
+#![cfg_attr(any(
+    target_arch = "arm",
+    target_arch = "mips",
+    target_arch = "mips64",
+    target_arch = "powerpc",
+    target_arch = "powerpc64",
+    target_arch = "sparc64",
+    target_arch = "x86"
+), feature(llvm_asm))]
 
 #[cfg(test)]
 extern crate std;