diff --git a/.github/workflows/test-release.yaml b/.github/workflows/test-release.yaml
index 906062c6..12beda75 100644
--- a/.github/workflows/test-release.yaml
+++ b/.github/workflows/test-release.yaml
@@ -249,6 +249,10 @@ jobs:
             setup: |
               sudo apt-get update
               sudo apt-get install -y gcc-powerpc64le-linux-gnu
+          - target: s390x-unknown-linux-gnu
+            setup: |
+              sudo apt-get update
+              sudo apt-get install -y gcc-s390x-linux-gnu
 
     steps:
       - uses: actions/checkout@v4
@@ -383,6 +387,12 @@ jobs:
             arch: 'ppc64'
             libc: 'gnu'
             without-lerna: true
+          - image: 'node:{:version}-slim'
+            target: s390x-unknown-linux-gnu
+            args: '--platform linux/s390x'
+            arch: 's390x'
+            libc: 'gnu'
+            without-lerna: true
           - image: 'node:{:version}-alpine'
             target: x86_64-unknown-linux-musl
             args: ''
diff --git a/cli/src/api/templates/ci-template.ts b/cli/src/api/templates/ci-template.ts
index 75fde639..f9750498 100644
--- a/cli/src/api/templates/ci-template.ts
+++ b/cli/src/api/templates/ci-template.ts
@@ -85,6 +85,12 @@ jobs:
               sudo apt-get update
               sudo apt-get install gcc-powerpc64le-linux-gnu -y
             build: ${packageManager} build --platform --target powerpc64le-unknown-linux-gnu
+          - host: ubuntu-latest
+            target: 's390x-unknown-linux-gnu'
+            setup: |
+              sudo apt-get update
+              sudo apt-get install gcc-s390x-linux-gnu -y
+            build: ${packageManager} build --platform --target s390x-unknown-linux-gnu
           - host: ubuntu-latest
             target: 'wasm32-wasi-preview1-threads'
             build: ${packageManager} build --platform --target wasm32-wasi-preview1-threads
diff --git a/cli/src/utils/__tests__/__snapshots__/target.spec.ts.md b/cli/src/utils/__tests__/__snapshots__/target.spec.ts.md
index 6403f629..03e88728 100644
--- a/cli/src/utils/__tests__/__snapshots__/target.spec.ts.md
+++ b/cli/src/utils/__tests__/__snapshots__/target.spec.ts.md
@@ -128,6 +128,13 @@ Generated by [AVA](https://avajs.dev).
         platformArchABI: 'linux-ppc64-gnu',
         triple: 'powerpc64le-unknown-linux-gnu',
       },
+      {
+        abi: 'gnu',
+        arch: 's390x',
+        platform: 'linux',
+        platformArchABI: 'linux-s390x-gnu',
+        triple: 's390x-unknown-linux-gnu',
+      },
       {
         abi: 'wasi',
         arch: 'wasm32',
diff --git a/cli/src/utils/__tests__/__snapshots__/target.spec.ts.snap b/cli/src/utils/__tests__/__snapshots__/target.spec.ts.snap
index 3c8261cf..fcec5bf4 100644
Binary files a/cli/src/utils/__tests__/__snapshots__/target.spec.ts.snap and b/cli/src/utils/__tests__/__snapshots__/target.spec.ts.snap differ
diff --git a/cli/src/utils/target.ts b/cli/src/utils/target.ts
index f120895c..fb58cba3 100644
--- a/cli/src/utils/target.ts
+++ b/cli/src/utils/target.ts
@@ -24,6 +24,7 @@ export const AVAILABLE_TARGETS = [
   'universal-apple-darwin',
   'riscv64gc-unknown-linux-gnu',
   'powerpc64le-unknown-linux-gnu',
+  's390x-unknown-linux-gnu',
   'wasm32-wasi-preview1-threads',
 ] as const
 
@@ -40,6 +41,7 @@ export const TARGET_LINKER: Record<string, string> = {
   'aarch64-unknown-linux-musl': 'aarch64-linux-musl-gcc',
   'riscv64gc-unknown-linux-gnu': 'riscv64-linux-gnu-gcc',
   'powerpc64le-unknown-linux-gnu': 'powerpc64le-linux-gnu-gcc',
+  's390x-unknown-linux-gnu': 's390x-linux-gnu-gcc',
 }
 
 // https://nodejs.org/api/process.html#process_process_arch
diff --git a/crates/napi/src/bindgen_runtime/js_values/bigint.rs b/crates/napi/src/bindgen_runtime/js_values/bigint.rs
index 5261e137..cd2da832 100644
--- a/crates/napi/src/bindgen_runtime/js_values/bigint.rs
+++ b/crates/napi/src/bindgen_runtime/js_values/bigint.rs
@@ -107,8 +107,7 @@ impl BigInt {
     if len == 1 {
       (self.words[0] as i128, false)
     } else {
-      let i128_words: [i64; 2] = [self.words[0] as _, self.words[1] as _];
-      let mut val = unsafe { ptr::read(i128_words.as_ptr() as *const i128) };
+      let mut val = self.words[0] as i128 + ((self.words[1] as i128) << 64);
       if self.sign_bit {
         val = -val;
       }
@@ -125,8 +124,7 @@ impl BigInt {
     if len == 1 {
       (self.sign_bit, self.words[0] as u128, false)
     } else {
-      let u128_words: [u64; 2] = [self.words[0], self.words[1]];
-      let val = unsafe { ptr::read(u128_words.as_ptr() as *const u128) };
+      let val = self.words[0] as u128 + ((self.words[1] as u128) << 64);
       (self.sign_bit, val, len > 2)
     }
   }
@@ -156,7 +154,16 @@ impl ToNapiValue for i128 {
   unsafe fn to_napi_value(env: sys::napi_env, val: Self) -> crate::Result<sys::napi_value> {
     let mut raw_value = ptr::null_mut();
     let sign_bit = i32::from(val <= 0);
-    let words = &val as *const i128 as *const u64;
+    if cfg!(target_endian = "little") {
+      let words = &val as *const i128 as *const u64;
+      check_status!(unsafe {
+        sys::napi_create_bigint_words(env, sign_bit, 2, words, &mut raw_value)
+      })?;
+      return Ok(raw_value);
+    }
+
+    let arr: [u64; 2] = [val as _, (val >> 64) as _];
+    let words = &arr as *const u64;
     check_status!(unsafe {
       sys::napi_create_bigint_words(env, sign_bit, 2, words, &mut raw_value)
     })?;
@@ -167,7 +174,14 @@ impl ToNapiValue for i128 {
 impl ToNapiValue for u128 {
   unsafe fn to_napi_value(env: sys::napi_env, val: Self) -> crate::Result<sys::napi_value> {
     let mut raw_value = ptr::null_mut();
-    let words = &val as *const u128 as *const u64;
+    if cfg!(target_endian = "little") {
+      let words = &val as *const u128 as *const u64;
+      check_status!(unsafe { sys::napi_create_bigint_words(env, 0, 2, words, &mut raw_value) })?;
+      return Ok(raw_value);
+    }
+
+    let arr: [u64; 2] = [val as _, (val >> 64) as _];
+    let words = &arr as *const u64;
     check_status!(unsafe { sys::napi_create_bigint_words(env, 0, 2, words, &mut raw_value) })?;
     Ok(raw_value)
   }
@@ -226,20 +240,19 @@ impl From<u64> for BigInt {
 impl From<i128> for BigInt {
   fn from(val: i128) -> Self {
     let sign_bit = val < 0;
-    let words = (if sign_bit { -val } else { val }).to_ne_bytes();
+    let val = if sign_bit { -val } else { val };
     BigInt {
       sign_bit,
-      words: unsafe { std::slice::from_raw_parts(words.as_ptr() as *mut _, 2).to_vec() },
+      words: vec![val as _, (val >> 64) as _],
     }
   }
 }
 
 impl From<u128> for BigInt {
   fn from(val: u128) -> Self {
-    let words = val.to_ne_bytes();
     BigInt {
       sign_bit: false,
-      words: unsafe { std::slice::from_raw_parts(words.as_ptr() as *mut _, 2).to_vec() },
+      words: vec![val as _, (val >> 64) as _],
     }
   }
 }
diff --git a/crates/napi/src/env.rs b/crates/napi/src/env.rs
index 25cf5db8..b27e30c4 100644
--- a/crates/napi/src/env.rs
+++ b/crates/napi/src/env.rs
@@ -119,7 +119,16 @@ impl Env {
   pub fn create_bigint_from_i128(&self, value: i128) -> Result<JsBigInt> {
     let mut raw_value = ptr::null_mut();
     let sign_bit = i32::from(value <= 0);
-    let words = &value as *const i128 as *const u64;
+    if cfg!(target_endian = "little") {
+      let words = &value as *const i128 as *const u64;
+      check_status!(unsafe {
+        sys::napi_create_bigint_words(self.0, sign_bit, 2, words, &mut raw_value)
+      })?;
+      return Ok(JsBigInt::from_raw_unchecked(self.0, raw_value, 2));
+    }
+
+    let arr: [u64; 2] = [value as _, (value >> 64) as _];
+    let words = &arr as *const u64;
     check_status!(unsafe {
       sys::napi_create_bigint_words(self.0, sign_bit, 2, words, &mut raw_value)
     })?;
@@ -129,7 +138,14 @@ impl Env {
   #[cfg(feature = "napi6")]
   pub fn create_bigint_from_u128(&self, value: u128) -> Result<JsBigInt> {
     let mut raw_value = ptr::null_mut();
-    let words = &value as *const u128 as *const u64;
+    if cfg!(target_endian = "little") {
+      let words = &value as *const u128 as *const u64;
+      check_status!(unsafe { sys::napi_create_bigint_words(self.0, 0, 2, words, &mut raw_value) })?;
+      return Ok(JsBigInt::from_raw_unchecked(self.0, raw_value, 2));
+    }
+
+    let arr: [u64; 2] = [value as _, (value >> 64) as _];
+    let words = &arr as *const u64;
     check_status!(unsafe { sys::napi_create_bigint_words(self.0, 0, 2, words, &mut raw_value) })?;
     Ok(JsBigInt::from_raw_unchecked(self.0, raw_value, 2))
   }
diff --git a/crates/napi/src/js_values/bigint.rs b/crates/napi/src/js_values/bigint.rs
index a72b44b0..0e96dbf8 100644
--- a/crates/napi/src/js_values/bigint.rs
+++ b/crates/napi/src/js_values/bigint.rs
@@ -246,17 +246,22 @@ impl JsBigInt {
   pub fn get_i128(&mut self) -> Result<(i128, bool)> {
     let (signed, words) = self.get_words()?;
 
-    let high_part = words.first().copied().unwrap_or(0).to_le_bytes();
-    let low_part = words.get(1).copied().unwrap_or(0).to_le_bytes();
+    let low_part = words.first().copied().unwrap_or(0).to_ne_bytes();
+    let high_part = words.get(1).copied().unwrap_or(0).to_ne_bytes();
 
     let mut val = [0_u8; std::mem::size_of::<i128>()];
-
-    let (high_val, low_val) = val.split_at_mut(low_part.len());
+    let high_val: &mut [u8];
+    let low_val: &mut [u8];
+    if cfg!(target_endian = "little") {
+      (low_val, high_val) = val.split_at_mut(low_part.len());
+    } else {
+      (high_val, low_val) = val.split_at_mut(low_part.len());
+    }
 
     high_val.copy_from_slice(&high_part);
     low_val.copy_from_slice(&low_part);
 
-    let mut val = i128::from_le_bytes(val);
+    let mut val = i128::from_ne_bytes(val);
 
     let mut loss = words.len() > 2;
     let mut overflow = false;
@@ -275,17 +280,23 @@ impl JsBigInt {
   pub fn get_u128(&mut self) -> Result<(bool, u128, bool)> {
     let (signed, words) = self.get_words()?;
 
-    let high_part = words.first().copied().unwrap_or(0).to_le_bytes();
-    let low_part = words.get(1).copied().unwrap_or(0).to_le_bytes();
+    let low_part = words.first().copied().unwrap_or(0).to_ne_bytes();
+    let high_part = words.get(1).copied().unwrap_or(0).to_ne_bytes();
 
-    let mut val = [0_u8; std::mem::size_of::<u128>()];
-
-    let (high_val, low_val) = val.split_at_mut(low_part.len());
+    let mut val = [0_u8; std::mem::size_of::<i128>()];
+    let high_val: &mut [u8];
+    let low_val: &mut [u8];
+    if cfg!(target_endian = "little") {
+      (low_val, high_val) = val.split_at_mut(low_part.len());
+    } else {
+      (high_val, low_val) = val.split_at_mut(low_part.len());
+    }
 
     high_val.copy_from_slice(&high_part);
     low_val.copy_from_slice(&low_part);
 
-    let val = u128::from_le_bytes(val);
+    let val = u128::from_ne_bytes(val);
+
     let len = words.len();
 
     Ok((signed, val, len > 2))
diff --git a/crates/napi/src/js_values/ser.rs b/crates/napi/src/js_values/ser.rs
index 9a53b2ba..42f4b3a1 100644
--- a/crates/napi/src/js_values/ser.rs
+++ b/crates/napi/src/js_values/ser.rs
@@ -1,6 +1,4 @@
 use std::result::Result as StdResult;
-#[cfg(feature = "napi6")]
-use std::slice;
 
 use serde::{ser, Serialize, Serializer};
 
@@ -124,12 +122,7 @@ impl<'env> Serializer for Ser<'env> {
 
   #[cfg(feature = "napi6")]
   fn serialize_u128(self, v: u128) -> Result<Self::Ok> {
-    let words_ref = &v as *const _;
-    let words = unsafe { slice::from_raw_parts(words_ref as *const u64, 2) };
-    self
-      .0
-      .create_bigint_from_words(false, words.to_vec())
-      .map(|v| v.raw)
+    self.0.create_bigint_from_u128(v).map(|v| v.raw)
   }
 
   #[cfg(all(
@@ -147,12 +140,7 @@ impl<'env> Serializer for Ser<'env> {
 
   #[cfg(feature = "napi6")]
   fn serialize_i128(self, v: i128) -> Result<Self::Ok> {
-    let words_ref = &(v as u128) as *const _;
-    let words = unsafe { slice::from_raw_parts(words_ref as *const u64, 2) };
-    self
-      .0
-      .create_bigint_from_words(v < 0, words.to_vec())
-      .map(|v| v.raw)
+    self.0.create_bigint_from_i128(v).map(|v| v.raw)
   }
 
   fn serialize_unit(self) -> Result<Self::Ok> {