1 files changed, 9 insertions, 0 deletions
diff --git a/components/style/selector_map.rs b/components/style/selector_map.rs
index cd99852861c..a53aad65fb3 100644
--- a/components/style/selector_map.rs
+++ b/components/style/selector_map.rs
@@ -500,6 +500,15 @@ fn specific_bucket_for<'a>(component: &'a Component<SelectorImpl>) -> Bucket<'a>
         // match the slotted <span>.
         Component::Slotted(ref selector) => find_bucket(selector.iter()),
         Component::Host(Some(ref selector)) => find_bucket(selector.iter()),
+        Component::Is(ref list) | Component::Where(ref list) => {
+            if list.len() == 1 {
+                find_bucket(list[0].iter())
+            } else {
+                // TODO(emilio): We should handle the multiple element case by
+                // inserting multiple entries in the map.
+                Bucket::Universal
+            }
+        },
         _ => Bucket::Universal,
     }
 }