diff --git a/test/unit/styling-cross-scope-var.html b/test/unit/styling-cross-scope-var.html
index 9e799124fb..4747494fe6 100644
--- a/test/unit/styling-cross-scope-var.html
+++ b/test/unit/styling-cross-scope-var.html
@@ -752,7 +752,8 @@
   suite('scoped-styling-var', function() {
 
   function assertComputed(element, value, pseudo, name) {
-    // force a style-recalc for Safari
+    // force a style-recalc for Safari missing updated CSS Custom Properties
+    // https://bugs.webkit.org/show_bug.cgi?id=170708
     element.offsetWidth;
     name = name || 'border-top-width';
     var computed = element.getComputedStyleValue && !pseudo ?
@@ -791,6 +792,7 @@
   test('instances of scoped @keyframes', function(done) {
     if (navigator.userAgent.match(/Safari\/603/) && ShadyCSS.nativeCss && ShadyCSS.nativeShadow) {
       // `:nth-of-type` is broken in shadow roots on Safari 10.1
+      // https://bugs.webkit.org/show_bug.cgi?id=166748
       this.skip();
     }
     var xKeyframes = styled.$.keyframes2;