diff --git a/src/context/mod.rs b/src/context/mod.rs
index ff08a78e0..20304c4bc 100644
--- a/src/context/mod.rs
+++ b/src/context/mod.rs
@@ -193,7 +193,7 @@ impl CallbackInfo<'_> {
         }
     }
 
-    pub fn len<'b, C: Context<'b>>(&self, cx: &C) -> i32 {
+    pub fn len<'b, C: Context<'b>>(&self, cx: &C) -> usize {
         unsafe { sys::call::len(cx.env().to_raw(), self.info) }
     }
 
@@ -652,7 +652,7 @@ impl<'a, T: This> CallContext<'a, T> {
     }
 
     /// Indicates the number of arguments that were passed to the function.
-    pub fn len(&self) -> i32 {
+    pub fn len(&self) -> usize {
         self.info.len(self)
     }
 
@@ -662,7 +662,7 @@ impl<'a, T: This> CallContext<'a, T> {
     }
 
     /// Produces the `i`th argument, or `None` if `i` is greater than or equal to `self.len()`.
-    pub fn argument_opt(&mut self, i: i32) -> Option<Handle<'a, JsValue>> {
+    pub fn argument_opt(&mut self, i: usize) -> Option<Handle<'a, JsValue>> {
         let argv = if let Some(argv) = self.arguments.as_ref() {
             argv
         } else {
@@ -670,12 +670,12 @@ impl<'a, T: This> CallContext<'a, T> {
             self.arguments.insert(argv)
         };
 
-        argv.get(i as usize)
+        argv.get(i)
             .map(|v| Handle::new_internal(JsValue::from_raw(self.env(), v)))
     }
 
     /// Produces the `i`th argument and casts it to the type `V`, or throws an exception if `i` is greater than or equal to `self.len()` or cannot be cast to `V`.
-    pub fn argument<V: Value>(&mut self, i: i32) -> JsResult<'a, V> {
+    pub fn argument<V: Value>(&mut self, i: usize) -> JsResult<'a, V> {
         match self.argument_opt(i) {
             Some(v) => v.downcast_or_throw(self),
             None => self.throw_type_error("not enough arguments"),
diff --git a/src/sys/call.rs b/src/sys/call.rs
index 0ee04e485..7176f27d8 100644
--- a/src/sys/call.rs
+++ b/src/sys/call.rs
@@ -53,7 +53,7 @@ pub unsafe fn this(env: Env, info: FunctionCallbackInfo, out: &mut Local) {
 
 /// Gets the number of arguments passed to the function.
 // TODO: Remove this when `CallContext` is refactored to get call info upfront.
-pub unsafe fn len(env: Env, info: FunctionCallbackInfo) -> i32 {
+pub unsafe fn len(env: Env, info: FunctionCallbackInfo) -> usize {
     let mut argc = 0usize;
     let status = napi::get_cb_info(
         env,
@@ -64,7 +64,7 @@ pub unsafe fn len(env: Env, info: FunctionCallbackInfo) -> i32 {
         null_mut(),
     );
     assert_eq!(status, napi::Status::Ok);
-    argc as i32
+    argc
 }
 
 /// Returns the function arguments for a call
diff --git a/test/napi/src/js/functions.rs b/test/napi/src/js/functions.rs
index 709489701..78ac033aa 100644
--- a/test/napi/src/js/functions.rs
+++ b/test/napi/src/js/functions.rs
@@ -139,11 +139,11 @@ pub fn construct_js_function_with_overloaded_result(mut cx: FunctionContext) ->
 }
 
 trait CheckArgument<'a> {
-    fn check_argument<V: Value>(&mut self, i: i32) -> JsResult<'a, V>;
+    fn check_argument<V: Value>(&mut self, i: usize) -> JsResult<'a, V>;
 }
 
 impl<'a, T: This> CheckArgument<'a> for CallContext<'a, T> {
-    fn check_argument<V: Value>(&mut self, i: i32) -> JsResult<'a, V> {
+    fn check_argument<V: Value>(&mut self, i: usize) -> JsResult<'a, V> {
         self.argument::<V>(i)
     }
 }
@@ -166,7 +166,7 @@ pub fn panic_after_throw(mut cx: FunctionContext) -> JsResult<JsUndefined> {
 
 pub fn num_arguments(mut cx: FunctionContext) -> JsResult<JsNumber> {
     let n = cx.len();
-    Ok(cx.number(n))
+    Ok(cx.number(n as i32))
 }
 
 pub fn return_this(mut cx: FunctionContext) -> JsResult<JsValue> {