diff --git a/README.md b/README.md
index b8b76ae1..a2c3aab2 100644
--- a/README.md
+++ b/README.md
@@ -31,8 +31,8 @@ A minimal library for building compiled `NodeJS` add-ons in `Rust`.
 ## NodeJS
 
 | Node10 | Node12 | Node14 | Node15 |
-| ------ | ------- | ------ | ------ |
-| ✓      | ✓       | ✓      | ✓      |
+| ------ | ------ | ------ | ------ |
+| ✓      | ✓      | ✓      | ✓      |
 
 This library depends on N-API and requires `Node@10.0.0` or later.
 
diff --git a/napi/src/env.rs b/napi/src/env.rs
index ecc3713a..e39fff6f 100644
--- a/napi/src/env.rs
+++ b/napi/src/env.rs
@@ -798,7 +798,10 @@ impl Env {
       )
     })?;
     if let Some(changed) = size_hint {
-      check_status!(unsafe { sys::napi_adjust_external_memory(self.0, changed, ptr::null_mut()) })?;
+      let mut adjusted_value = 0i64;
+      check_status!(unsafe {
+        sys::napi_adjust_external_memory(self.0, changed, &mut adjusted_value)
+      })?;
     };
     Ok(unsafe { JsExternal::from_raw_unchecked(self.0, object_value) })
   }
diff --git a/test_module/__test__/create-external.spec.ts b/test_module/__test__/create-external.spec.ts
index 1e2cc19f..a55c629f 100644
--- a/test_module/__test__/create-external.spec.ts
+++ b/test_module/__test__/create-external.spec.ts
@@ -7,3 +7,9 @@ test('should create external object and get it back', (t) => {
   const externalObject = bindings.createExternal(42)
   t.is(bindings.getExternalCount(externalObject), fixture)
 })
+
+test('should create external with size hint', (t) => {
+  const fixture = 42
+  const externalObject = bindings.createExternalWithHint(42)
+  t.is(bindings.getExternalCount(externalObject), fixture)
+})
diff --git a/test_module/src/external.rs b/test_module/src/external.rs
index c401ac4d..b31c698e 100644
--- a/test_module/src/external.rs
+++ b/test_module/src/external.rs
@@ -13,6 +13,13 @@ pub fn create_external(ctx: CallContext) -> Result<JsExternal> {
   ctx.env.create_external(native, None)
 }
 
+#[js_function(1)]
+pub fn create_external_with_hint(ctx: CallContext) -> Result<JsExternal> {
+  let count = ctx.get::<JsNumber>(0)?.try_into()?;
+  let native = NativeObject { count };
+  ctx.env.create_external(native, Some(5))
+}
+
 #[js_function(1)]
 pub fn get_external_count(ctx: CallContext) -> Result<JsNumber> {
   let attached_obj = ctx.get::<JsExternal>(0)?;
@@ -22,6 +29,7 @@ pub fn get_external_count(ctx: CallContext) -> Result<JsNumber> {
 
 pub fn register_js(exports: &mut JsObject) -> Result<()> {
   exports.create_named_method("createExternal", create_external)?;
+  exports.create_named_method("createExternalWithHint", create_external_with_hint)?;
   exports.create_named_method("getExternalCount", get_external_count)?;
   Ok(())
 }