diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 340cbde980b..4dcc6df054e 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -3119,6 +3119,18 @@
             "url": "/_mozilla/css/quotes_simple_a.html"
           }
         ],
+        "css/restyle_hints_attr.html": [
+          {
+            "path": "css/restyle_hints_attr.html",
+            "references": [
+              [
+                "/_mozilla/css/restyle_hints_attr_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/restyle_hints_attr.html"
+          }
+        ],
         "css/restyle_hints_state.html": [
           {
             "path": "css/restyle_hints_state.html",
@@ -8052,6 +8064,18 @@
           "url": "/_mozilla/css/quotes_simple_a.html"
         }
       ],
+      "css/restyle_hints_attr.html": [
+        {
+          "path": "css/restyle_hints_attr.html",
+          "references": [
+            [
+              "/_mozilla/css/restyle_hints_attr_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/restyle_hints_attr.html"
+        }
+      ],
       "css/restyle_hints_state.html": [
         {
           "path": "css/restyle_hints_state.html",
diff --git a/tests/wpt/mozilla/tests/css/restyle_hints_attr.css b/tests/wpt/mozilla/tests/css/restyle_hints_attr.css
new file mode 100644
index 00000000000..64d332c31f7
--- /dev/null
+++ b/tests/wpt/mozilla/tests/css/restyle_hints_attr.css
@@ -0,0 +1,44 @@
+div {
+  background-color: black;
+  padding: 10px;
+  width: 50px;
+  height: 50px;
+  color: gray;
+}
+
+div[foo=kokosnuss] {
+  background: black;
+}
+
+div[foo][bar] {
+  background: red;
+}
+
+div[foo=kokosnuss][bar~=fett] {
+  background: green;
+}
+
+div[bar] > div[baz] div {
+  color: cyan;
+}
+
+div[foo][bar~=butter] div {
+  background: purple;
+  color: white;
+}
+
+div[foo][bar~=butter] > div {
+  background: yellow;
+}
+
+div[bar~=butter][foo=kokosnuss] + div {
+  background: pink;
+}
+
+div[foo=kokosnuss] ~ div {
+  background: green;
+}
+
+div + div[foo=keine][bar=ahnung] {
+  background: lavender;
+}
diff --git a/tests/wpt/mozilla/tests/css/restyle_hints_attr.html b/tests/wpt/mozilla/tests/css/restyle_hints_attr.html
new file mode 100644
index 00000000000..d9c55498f8f
--- /dev/null
+++ b/tests/wpt/mozilla/tests/css/restyle_hints_attr.html
@@ -0,0 +1,35 @@
+<!doctype html>
+<meta charset="utf-8">
+<title></title>
+<link rel="match" href="restyle_hints_attr_ref.html">
+<link rel="stylesheet" href="restyle_hints_attr.css">
+<body>
+  <div id="d1">
+    <div id="d2">
+      <div>some text</div>
+    </div>
+  </div>
+  <div id="d3" foo="keine" bar="ahnung"></div>
+  <div id="d4"></div>
+  <div></div>
+  <script>
+    window.dummy = 0;
+    var $ = document.getElementById.bind(document);
+    function syncRestyle() { window.dummy += document.body.lastElementChild.offsetTop; }
+    $('d1').setAttribute("foo", "kokosnuss");
+    syncRestyle();
+    $('d1').setAttribute("bar", "butter");
+    syncRestyle();
+    $('d4').setAttribute("foo", true);
+    syncRestyle();
+    $('d4').setAttribute("bar", true);
+    syncRestyle();
+    $('d2').setAttribute("baz", "lecker");
+    syncRestyle();
+    $('d1').setAttribute("bar", "fett butter");
+    syncRestyle();
+    $('d3').removeAttribute("bar");
+    syncRestyle();
+  </script>
+</body>
+</html>
diff --git a/tests/wpt/mozilla/tests/css/restyle_hints_attr_ref.html b/tests/wpt/mozilla/tests/css/restyle_hints_attr_ref.html
new file mode 100644
index 00000000000..2d87a0f4526
--- /dev/null
+++ b/tests/wpt/mozilla/tests/css/restyle_hints_attr_ref.html
@@ -0,0 +1,16 @@
+<!doctype html>
+<meta charset="utf-8">
+<link rel="stylesheet" href="restyle_hints_attr.css">
+<title></title>
+<body>
+  <div foo="kokosnuss" bar="butter fett">
+    <div baz="lecker">
+      <div>some text</div>
+    </div>
+  </div>
+  <div></div>
+  <div bar foo></div>
+  <div></div>
+</body>
+</html>
+
diff --git a/tests/wpt/mozilla/tests/css/restyle_hints_state.html b/tests/wpt/mozilla/tests/css/restyle_hints_state.html
index 52f82bc905d..480d1675bb5 100644
--- a/tests/wpt/mozilla/tests/css/restyle_hints_state.html
+++ b/tests/wpt/mozilla/tests/css/restyle_hints_state.html
@@ -30,8 +30,9 @@
      * implement attribute-based restyle hints, we can stop dirtying the subtree
      * on attribute modifications, and these tests will start to be more useful.
      */
+    window.dummy = 0;
     var $ = document.getElementById.bind(document);
-    function syncRestyle() { window.dummy != $("fs2").offsetTop; }
+    function syncRestyle() { window.dummy += $("fs2").offsetTop; }
     syncRestyle();
     $('fs1').disabled = true;
     syncRestyle();
