diff --git a/lib/Document.js b/lib/Document.js
index 4020f745..a1b0fccb 100644
--- a/lib/Document.js
+++ b/lib/Document.js
@@ -757,7 +757,7 @@ Document.prototype = Object.create(ContainerNode.prototype, {
   }},
 
   querySelector: { value: function(selector) {
-    return select(selector, this)[0];
+    return select(selector, this)[0] ?? null;
   }},
 
   querySelectorAll: { value: function(selector) {
diff --git a/lib/Element.js b/lib/Element.js
index 097ba75e..3fb87c88 100644
--- a/lib/Element.js
+++ b/lib/Element.js
@@ -955,7 +955,7 @@ Element.prototype = Object.create(ContainerNode.prototype, {
   }},
 
   querySelector: { value: function(selector) {
-    return select(selector, this)[0];
+    return select(selector, this)[0] ?? null;
   }},
 
   querySelectorAll: { value: function(selector) {
diff --git a/test/domino.js b/test/domino.js
index a49ab1fe..2d0bbdcf 100644
--- a/test/domino.js
+++ b/test/domino.js
@@ -61,6 +61,13 @@ exports.closest = function() {
   (r8 === null).should.be.true();
 };
 
+exports.querySelector = function() {
+  var window = createWindow(html);
+  var d = window.document;
+  var nothing = d.querySelector('.foobar');
+  (nothing === null).should.be.true();
+};
+
 exports.querySelectorAll = function() {
   var window = createWindow(html);
   var d = window.document;
@@ -838,7 +845,7 @@ exports.eqAttr = function() {
   var html = "<div id=a ==x><a=B></A=b></div>";
   var doc = domino.createDocument(html);
   var div = doc.querySelector('#a');
-  (div != null).should.be.true(); // jshint ignore:line
+  (div !== null).should.be.true(); // jshint ignore:line
   div.attributes.length.should.equal(2);
   div.attributes.item(1).name.should.equal('=');
   div.children.length.should.equal(1);
@@ -1681,7 +1688,7 @@ exports.emptyAttributeTokenSelectors = {
             var queryContext = root.nodeName + ': ' + context;
             assert.strictEqual(root.querySelectorAll(selector).length, 0, queryContext);
             // Preserve Domino's existing no-match return value.
-            assert.strictEqual(root.querySelector(selector), undefined, queryContext);
+            assert.strictEqual(root.querySelector(selector), null, queryContext);
           });
           assert.strictEqual(meta.matches(selector), false, context);
           assert.strictEqual(meta.closest(selector), null, context);