diff --git a/crates/webidl/src/idl_type.rs b/crates/webidl/src/idl_type.rs
index 7d4cd81e..be96d596 100644
--- a/crates/webidl/src/idl_type.rs
+++ b/crates/webidl/src/idl_type.rs
@@ -481,7 +481,15 @@ impl<'a> IdlType<'a> {
             IdlType::Nullable(idl_type) => Some(option_ty(idl_type.to_syn_type(pos)?)),
             IdlType::FrozenArray(_idl_type) => None,
             IdlType::Sequence(_idl_type) => None,
-            IdlType::Promise(_idl_type) => None,
+            IdlType::Promise(_idl_type) => {
+                let path = vec![rust_ident("js_sys"), rust_ident("Promise")];
+                let ty = leading_colon_path_ty(path);
+                if pos == TypePosition::Argument {
+                    Some(shared_ref(ty))
+                } else {
+                    Some(ty)
+                }
+            }
             IdlType::Record(_idl_type_from, _idl_type_to) => None,
             IdlType::Union(_idl_types) => None,
 
diff --git a/crates/webidl/src/lib.rs b/crates/webidl/src/lib.rs
index bb8bab71..ed6ab3af 100644
--- a/crates/webidl/src/lib.rs
+++ b/crates/webidl/src/lib.rs
@@ -117,7 +117,7 @@ fn compile_ast(mut ast: backend::ast::Program) -> String {
         vec![
             "str", "char", "bool", "JsValue", "u8", "i8", "u16", "i16", "u32", "i32", "u64", "i64",
             "usize", "isize", "f32", "f64", "Result", "String", "Vec", "Option",
-            "ArrayBuffer", "Object",
+            "ArrayBuffer", "Object", "Promise",
         ].into_iter()
             .map(|id| proc_macro2::Ident::new(id, proc_macro2::Span::call_site())),
     );