diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 0bcfe33f..aeaefd7a 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -219,6 +219,24 @@ jobs:
       - name: Test (custom getrandom)
         run: cargo test --target=wasm32-unknown-unknown --features=custom
 
+  wasm64-tests:
+    name: WASM memory64
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: nightly
+          components: rust-src
+          override: true
+      - uses: Swatinem/rust-cache@v1
+      - name: Build and Link tests (build-std)
+        # This target is Tier 3, so we have to build libstd ourselves.
+        # We currently cannot run these tests because wasm-bindgen-test-runner
+        # does not yet support memory64.
+        run: cargo test --no-run -Z build-std=std,panic_abort --target=wasm64-unknown-unknown --features=js
+
   wasi-tests:
     name: WASI test
     runs-on: ubuntu-latest
diff --git a/Cargo.toml b/Cargo.toml
index 320aa581..35408b83 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,10 +23,10 @@ libc = { version = "0.2.128", default-features = false }
 [target.'cfg(target_os = "wasi")'.dependencies]
 wasi = { version = "0.11", default-features = false }
 
-[target.'cfg(all(target_arch = "wasm32", target_os = "unknown"))'.dependencies]
+[target.'cfg(all(any(target_arch = "wasm32", target_arch = "wasm64"), target_os = "unknown"))'.dependencies]
 wasm-bindgen = { version = "0.2.62", default-features = false, optional = true }
 js-sys = { version = "0.3", optional = true }
-[target.'cfg(all(target_arch = "wasm32", target_os = "unknown"))'.dev-dependencies]
+[target.'cfg(all(any(target_arch = "wasm32", target_arch = "wasm64"), target_os = "unknown"))'.dev-dependencies]
 wasm-bindgen-test = "0.3.18"
 
 [features]
@@ -34,7 +34,7 @@ wasm-bindgen-test = "0.3.18"
 std = []
 # Feature to enable fallback RDRAND-based implementation on x86/x86_64
 rdrand = []
-# Feature to enable JavaScript bindings on wasm32-unknown-unknown
+# Feature to enable JavaScript bindings on wasm*-unknown-unknown
 js = ["wasm-bindgen", "js-sys"]
 # Feature to enable custom RNG implementations
 custom = []
diff --git a/src/js.rs b/src/js.rs
index 7b9ae313..e692a1bd 100644
--- a/src/js.rs
+++ b/src/js.rs
@@ -16,6 +16,8 @@ use wasm_bindgen::{prelude::wasm_bindgen, JsCast, JsValue};
 // Size of our temporary Uint8Array buffer used with WebCrypto methods
 // Maximum is 65536 bytes see https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues
 const WEB_CRYPTO_BUFFER_SIZE: usize = 256;
+// Node.js's crypto.randomFillSync requires the size to be less than 2**31.
+const NODE_MAX_BUFFER_SIZE: usize = (1 << 31) - 1;
 
 enum RngSource {
     Node(NodeCrypto),
@@ -38,8 +40,10 @@ pub(crate) fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error>
                 // have to ensure the memory in `dest` is initialized.
                 let dest = uninit_slice_fill_zero(dest);
 
-                if n.random_fill_sync(dest).is_err() {
-                    return Err(Error::NODE_RANDOM_FILL_SYNC);
+                for chunk in dest.chunks_mut(NODE_MAX_BUFFER_SIZE) {
+                    if n.random_fill_sync(chunk).is_err() {
+                        return Err(Error::NODE_RANDOM_FILL_SYNC);
+                    }
                 }
             }
             RngSource::Web(crypto, buf) => {
diff --git a/src/lib.rs b/src/lib.rs
index 36a49c01..6f9fcd8a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -30,7 +30,7 @@
 //! | ESP-IDF           | `*‑espidf`         | [`esp_fill_random`]
 //! | Emscripten        | `*‑emscripten`     | `/dev/urandom` (identical to `/dev/random`)
 //! | WASI              | `wasm32‑wasi`      | [`random_get`]
-//! | Web Browser and Node.js | `wasm32‑*‑unknown` | [`Crypto.getRandomValues`] if available, then [`crypto.randomFillSync`] if on Node.js, see [WebAssembly support]
+//! | Web Browser and Node.js | `wasm*‑*‑unknown` | [`Crypto.getRandomValues`] if available, then [`crypto.randomFillSync`] if on Node.js, see [WebAssembly support]
 //! | SOLID             | `*-kmc-solid_*`    | `SOLID_RNG_SampleRandomBytes`
 //! | Nintendo 3DS      | `armv6k-nintendo-3ds` | [`getrandom`][1]
 //!
@@ -262,12 +262,14 @@ cfg_if! {
                         any(target_arch = "x86_64", target_arch = "x86")))] {
         #[path = "rdrand.rs"] mod imp;
     } else if #[cfg(all(feature = "js",
-                        target_arch = "wasm32", target_os = "unknown"))] {
+                        any(target_arch = "wasm32", target_arch = "wasm64"),
+                        target_os = "unknown"))] {
         #[path = "js.rs"] mod imp;
     } else if #[cfg(feature = "custom")] {
         use custom as imp;
-    } else if #[cfg(all(target_arch = "wasm32", target_os = "unknown"))] {
-        compile_error!("the wasm32-unknown-unknown target is not supported by \
+    } else if #[cfg(all(any(target_arch = "wasm32", target_arch = "wasm64"),
+                        target_os = "unknown"))] {
+        compile_error!("the wasm*-unknown-unknown targets are not supported by \
                         default, you may need to enable the \"js\" feature. \
                         For more information see: \
                         https://docs.rs/getrandom/#webassembly-support");