--- a/servo/components/style/invalidation/stylesheets.rs
+++ b/servo/components/style/invalidation/stylesheets.rs
@@ -149,16 +149,21 @@ impl StylesheetInvalidationSet {
 
         if self.fully_invalid {
             debug!("process_invalidations_in_subtree: fully_invalid({:?})",
                    element);
             data.ensure_restyle().hint.insert(StoredRestyleHint::subtree());
             return true;
         }
 
+        if self.invalid_scopes.is_empty() {
+            debug!("process_invalidations_in_subtree: empty invalidation set");
+            return false;
+        }
+
         for scope in &self.invalid_scopes {
             if scope.matches(element) {
                 debug!("process_invalidations_in_subtree: {:?} matched {:?}",
                        element, scope);
                 data.ensure_restyle().hint.insert(StoredRestyleHint::subtree());
                 return true;
             }
         }