diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 60184f7..285b04b 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -46,14 +46,17 @@ jobs:
         run: cargo test
 
   miri:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest]
     steps:
       - uses: actions/checkout@v5
       - name: Setup Rust
         uses: dtolnay/rust-toolchain@stable
         with:
-          targets: x86_64-unknown-linux-gnu
-          components: miri
+          components: miri,rust-src
           toolchain: nightly
       - uses: actions/setup-node@v5
         with:
diff --git a/src/simd/avx512.rs b/src/simd/avx512.rs
index 316edd2..a1ac242 100644
--- a/src/simd/avx512.rs
+++ b/src/simd/avx512.rs
@@ -211,8 +211,9 @@ pub unsafe fn format_string(value: &str, dst: &mut [u8]) -> usize {
 
         // Handle remaining bytes
         let mut placeholder: [u8; LANES] = [0; LANES];
+        let mut v;
         while nb > 0 {
-            let v = {
+            v = {
                 #[cfg(not(any(target_os = "linux", target_os = "macos")))]
                 {
                     std::ptr::copy_nonoverlapping(sptr, placeholder[..].as_mut_ptr(), nb);
@@ -237,7 +238,7 @@ pub unsafe fn format_string(value: &str, dst: &mut [u8]) -> usize {
                 }
             };
 
-            v.storeu(dptr);
+            v.storeu(std::slice::from_raw_parts_mut(dptr, LANES).as_mut_ptr());
             let mask = escaped_mask(v).clear_high_bits(LANES - nb);
 
             if mask.all_zero() {