diff --git a/js/core/templates/webidl-contiguous/serializer.html b/js/core/templates/webidl-contiguous/serializer.html
deleted file mode 100644
index 8dfbd5c499..0000000000
--- a/js/core/templates/webidl-contiguous/serializer.html
+++ /dev/null
@@ -1,3 +0,0 @@
-<span class='idlSerializer' id="{{obj.idlId}}" data-idl data-title='serializer'>{{extAttr obj indent
-}}{{idn indent}}{{#tryLink obj}}serializer{{/tryLink
-}}{{#if values}} = <span class='idlSerializerValues'>{{values}}</span>{{/if}};</span>
diff --git a/package.json b/package.json
index 0465ce2eff..9669b654e2 100644
--- a/package.json
+++ b/package.json
@@ -51,7 +51,7 @@
     "text": "github:requirejs/text",
     "uglify-es": "^3.0.20",
     "url-search-params": "^0.9.0",
-    "webidl2": "^3.0.2"
+    "webidl2": "^4.0.0"
   },
   "scripts": {
     "babel:build": "babel src -d js --source-maps",
diff --git a/src/core/webidl.js b/src/core/webidl.js
index 1ade1fc0b9..07d34d2db1 100644
--- a/src/core/webidl.js
+++ b/src/core/webidl.js
@@ -28,7 +28,6 @@ var idlMaplikeTmpl = tmpls["maplike.html"];
 var idlMethodTmpl = tmpls["method.html"];
 var idlMultiLineCommentTmpl = tmpls["multiline-comment.html"];
 var idlParamTmpl = tmpls["param.html"];
-var idlSerializerTmpl = tmpls["serializer.html"];
 var idlTypedefTmpl = tmpls["typedef.html"];
 // TODO: make these linkable somehow.
 // https://github.com/w3c/respec/issues/999
@@ -426,7 +425,6 @@ const idlKeywords = new Set([
   "RegExp",
   "required",
   "sequence",
-  "serializer",
   "setlike",
   "setter",
   "short",
@@ -457,7 +455,6 @@ const argumentNameKeyword = new Set([
   "maplike",
   "partial",
   "required",
-  "serializer",
   "setlike",
   "setter",
   "static",
@@ -646,7 +643,6 @@ function writeInterfaceDefinition(opt, callback) {
   obj.members.forEach(function(it) {
     if (
       typeIsWhitespace(it.type) ||
-      it.type === "serializer" ||
       it.type === "maplike" ||
       it.type === "iterable"
     ) {
@@ -671,8 +667,6 @@ function writeInterfaceDefinition(opt, callback) {
           return writeMethod(ch, maxMeth, indent + 1);
         case "const":
           return writeConst(ch, maxConst, indent + 1);
-        case "serializer":
-          return writeSerializer(ch, indent + 1);
         case "maplike":
           return writeMaplike(ch, indent + 1);
         case "iterable":
@@ -749,7 +743,6 @@ function writeMethod(meth, max, indent) {
     "setter",
     "deleter",
     "legacycaller",
-    "serializer",
     "stringifier",
   ];
   var special = "";
@@ -824,22 +817,6 @@ function writeMultiLineComment(comment, indent) {
   });
 }
 
-function writeSerializer(serializer, indent) {
-  var values = "";
-  if (serializer.patternMap) {
-    values = "{" + serializer.names.join(", ") + "}";
-  } else if (serializer.patternList) {
-    values = "[" + serializer.patternList.join(", ") + "]";
-  } else if (serializer.name) {
-    values = serializer.name;
-  }
-  return idlSerializerTmpl({
-    obj: serializer,
-    indent: indent,
-    values: values,
-  });
-}
-
 function writeMaplike(maplike, indent) {
   var qualifiers = "";
   if (maplike.readonly) qualifiers += "readonly ";
@@ -947,8 +924,7 @@ function linkDefinitions(parse, definitionMap, parent, idlElem) {
           defn.setter ||
           defn.deleter ||
           defn.legacycaller ||
-          defn.stringifier ||
-          defn.serializer
+          defn.stringifier
         ) {
           name = "";
         }
@@ -978,12 +954,6 @@ function linkDefinitions(parse, definitionMap, parent, idlElem) {
         defn.idlId =
           "idl-def-" + parent.toLowerCase() + "-" + name.toLowerCase();
         break;
-      case "serializer":
-        name = "serializer";
-        defn.idlId =
-          "idl-def-" + parent.toLowerCase() + "-" + name.toLowerCase();
-        break;
-
       case "implements":
       case "ws":
       case "ws-pea":
@@ -1170,7 +1140,7 @@ export function run(conf, doc, cb) {
     $df.attr({ id: this.id });
     $df
       .find(
-        ".idlAttribute,.idlCallback,.idlConst,.idlDictionary,.idlEnum,.idlException,.idlField,.idlInterface,.idlMember,.idlMethod,.idlSerializer,.idlMaplike,.idlIterable,.idlTypedef"
+        ".idlAttribute,.idlCallback,.idlConst,.idlDictionary,.idlEnum,.idlException,.idlField,.idlInterface,.idlMember,.idlMethod,.idlMaplike,.idlIterable,.idlTypedef"
       )
       .each(function() {
         var elem = $(this);
diff --git a/tests/spec/core/webidl-spec.js b/tests/spec/core/webidl-spec.js
index 0c57391172..f59d0563a7 100644
--- a/tests/spec/core/webidl-spec.js
+++ b/tests/spec/core/webidl-spec.js
@@ -378,30 +378,6 @@ describe("Core - WebIDL", function() {
     done();
   });
 
-  it("should handle serializer", function(done) {
-    var $target = $("#serializer-map", doc);
-    var text =
-      "interface SerializerMap {\n" +
-      "    attribute DOMString foo;\n" +
-      "    attribute DOMString bar;\n" +
-      "    serializer = {foo, bar};\n" +
-      "};";
-    expect($target.text()).toEqual(text);
-    expect($target.find(".idlSerializer").length).toEqual(1);
-    var $serializer = $target.find(".idlSerializer").first();
-    expect($serializer.find(".idlSerializerValues").text()).toEqual(
-      "{foo, bar}"
-    );
-
-    // Links and IDs.
-    $serializer = $target.find(".idlSerializer:contains('serializer')");
-    expect($serializer.attr("id")).toEqual("idl-def-serializermap-serializer");
-    expect($serializer.children("a").attr("href")).toEqual(
-      "#dom-serializermap-serializer"
-    );
-    done();
-  });
-
   it("should handle comments", function(done) {
     var $target = $("#comments-basic", doc);
     var // TODO: Handle comments when WebIDL2 does.
diff --git a/tests/spec/core/webidl.html b/tests/spec/core/webidl.html
index 661d5859ea..b64e18de71 100644
--- a/tests/spec/core/webidl.html
+++ b/tests/spec/core/webidl.html
@@ -348,17 +348,6 @@ <h2>Operations</h2>
         <dfn>ull</dfn> is a method. Its <dfn data-lt="ull!overload-1">overloaded form</dfn> returns a <code>SuperStar/</code>
       </p>
     </section>
-    <section>
-      <h2>Serializer</h2>
-      <pre id='serializer-map' class='idl'>
-        interface SerializerMap {
-          attribute DOMString foo;
-          attribute DOMString bar;
-          serializer = { foo, bar };
-        };
-      </pre>
-      <p id='serializer-map-doc'><dfn for="SerializerMap">serializer</dfn> serializes a SerializerMap.</p>
-    </section>
     <section>
       <h2>Comments</h2>
       <pre id="comments-basic" class='idl'>