diff --git a/crates/js-sys/src/lib.rs b/crates/js-sys/src/lib.rs
index 8af6e90065b..d923a7bbb8b 100644
--- a/crates/js-sys/src/lib.rs
+++ b/crates/js-sys/src/lib.rs
@@ -4444,8 +4444,8 @@ pub mod Intl {
         /// object.
         ///
         /// [MDN documentation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Collator/compare)
-        #[wasm_bindgen(method, getter, js_class = "Intl.Collator")]
-        pub fn compare(this: &Collator) -> Function;
+        #[wasm_bindgen(method, js_class = "Intl.Collator")]
+        pub fn compare(this: &Collator, string1: &str, string2: &str) -> i32;
 
         /// The `Intl.Collator.prototype.resolvedOptions()` method returns a new
         /// object with properties reflecting the locale and collation options
@@ -4488,8 +4488,8 @@ pub mod Intl {
         /// Intl.DateTimeFormat object.
         ///
         /// [MDN documentation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DateTimeFormat/format)
-        #[wasm_bindgen(method, getter, js_class = "Intl.DateTimeFormat")]
-        pub fn format(this: &DateTimeFormat) -> Function;
+        #[wasm_bindgen(method, js_class = "Intl.DateTimeFormat")]
+        pub fn format(this: &DateTimeFormat, date: &Date) -> JsString;
 
         /// The `Intl.DateTimeFormat.prototype.formatToParts()` method allows locale-aware
         /// formatting of strings produced by DateTimeFormat formatters.
@@ -4539,8 +4539,8 @@ pub mod Intl {
         /// NumberFormat object.
         ///
         /// [MDN documentation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NumberFormat/format)
-        #[wasm_bindgen(method, getter, js_class = "Intl.NumberFormat")]
-        pub fn format(this: &NumberFormat) -> Function;
+        #[wasm_bindgen(method, js_class = "Intl.NumberFormat")]
+        pub fn format(this: &NumberFormat, number: f64) -> JsString;
 
         /// The `Intl.Numberformat.prototype.formatToParts()` method allows locale-aware
         /// formatting of strings produced by NumberTimeFormat formatters.
diff --git a/crates/js-sys/tests/wasm/Intl.rs b/crates/js-sys/tests/wasm/Intl.rs
index 427ea00a5da..396a4a2624b 100644
--- a/crates/js-sys/tests/wasm/Intl.rs
+++ b/crates/js-sys/tests/wasm/Intl.rs
@@ -30,7 +30,9 @@ fn collator() {
     let opts = Object::new();
 
     let c = Intl::Collator::new(&locales, &opts);
-    assert!(c.compare().is_instance_of::<Function>());
+    assert_eq!(c.compare("a", "b"), -1);
+    assert_eq!(c.compare("a", "a"), 0);
+    assert_eq!(c.compare("b", "a"), 1);
     assert!(c.resolved_options().is_instance_of::<Object>());
 
     let a = Intl::Collator::supported_locales_of(&locales, &opts);
@@ -55,7 +57,7 @@ fn date_time_format() {
     let epoch = Date::new(&JsValue::from(0));
 
     let c = Intl::DateTimeFormat::new(&locales, &opts);
-    assert!(c.format().is_instance_of::<Function>());
+    assert!(c.format(&epoch).is_string());
     assert!(c.format_to_parts(&epoch).is_instance_of::<Array>());
     assert!(c.resolved_options().is_instance_of::<Object>());
 
@@ -80,7 +82,7 @@ fn number_format() {
     let opts = Object::new();
 
     let n = Intl::NumberFormat::new(&locales, &opts);
-    assert!(n.format().is_instance_of::<Function>());
+    assert_eq!(n.format(42.5), JsString::from("42.5"));
     assert!(n.format_to_parts(42.5).is_instance_of::<Array>());
     assert!(n.resolved_options().is_instance_of::<Object>());