diff --git a/crates/webidl/Cargo.toml b/crates/webidl/Cargo.toml
index b5183178e88..f7547ce40d6 100644
--- a/crates/webidl/Cargo.toml
+++ b/crates/webidl/Cargo.toml
@@ -20,7 +20,7 @@ heck = "0.3"
 log = "0.4.1"
 proc-macro2 = "1.0"
 quote = '1.0'
-syn = { version = '2.0', features = ['full'] }
+syn = { version = '2.0', features = ['full', 'extra-traits'] }
 wasm-bindgen-backend = { version = "=0.2.90", path = "../backend" }
 weedle = { git = "https://github.com/rustwasm/weedle.git" }
 once_cell = "1.12"
diff --git a/crates/webidl/src/generator.rs b/crates/webidl/src/generator.rs
index 54cd624a605..3f1552dc444 100644
--- a/crates/webidl/src/generator.rs
+++ b/crates/webidl/src/generator.rs
@@ -5,10 +5,13 @@ use quote::quote;
 use std::collections::BTreeSet;
 use std::str::FromStr;
 use syn::{Ident, Type};
+use wasm_bindgen_backend::util::leading_colon_path_ty;
 use wasm_bindgen_backend::util::{raw_ident, rust_ident};
 
 use crate::constants::{BUILTIN_IDENTS, POLYFILL_INTERFACES};
 use crate::traverse::TraverseType;
+use crate::util::option_ty;
+use crate::util::shared_ref;
 use crate::util::{get_cfg_features, mdn_doc, required_doc_string, snake_case_ident};
 use crate::Options;
 
@@ -642,6 +645,18 @@ impl DictionaryField {
         let js_name_ts = TokenStream::from_str(&self.js_name)
             .expect("The JS attribute name should be convertible to a tokenstream");
 
+        let js_value_ref_type = shared_ref(
+            leading_colon_path_ty(vec![rust_ident("wasm_bindgen"), rust_ident("JsValue")]),
+            false,
+        );
+        let js_value_ref_option_type = option_ty(js_value_ref_type.clone());
+
+        let ty = if ty == &js_value_ref_option_type {
+            js_value_ref_type
+        } else {
+            ty.clone()
+        };
+
         quote! {
             #cfg_features
             #[wasm_bindgen(method, setter = #js_name_ts)]
@@ -673,13 +688,25 @@ impl DictionaryField {
 
         let shim_name = self.shim_name();
 
+        let js_value_ref_type = shared_ref(
+            leading_colon_path_ty(vec![rust_ident("wasm_bindgen"), rust_ident("JsValue")]),
+            false,
+        );
+        let js_value_ref_option_type = option_ty(js_value_ref_type.clone());
+
+        let shim_args = if ty == &js_value_ref_option_type {
+            quote! { val.unwrap_or(#js_value_ref_type::NULL) }
+        } else {
+            quote! { val }
+        };
+
         quote! {
             #unstable_attr
             #cfg_features
             #doc_comment
             #unstable_docs
             pub fn #name(&mut self, val: #ty) -> &mut Self {
-                self.#shim_name(val);
+                self.#shim_name(#shim_args);
                 self
             }
         }