--- a/servo/components/style/dom_apis.rs
+++ b/servo/components/style/dom_apis.rs
@@ -526,17 +526,17 @@ where
     //
     // See the comment in collect_invalidations to see why only if we're a root.
     //
     // The invalidation mechanism is only useful in presence of combinators.
     //
     // We could do that check properly here, though checking the length of the
     // selectors is a good heuristic.
     let invalidation_may_be_useful =
-        selector_list.0.iter().any(|s| s.len() > 1);
+        selector_list.0.iter().any(|s| s.len() > 2);
 
     if root_element.is_some() || !invalidation_may_be_useful {
         query_selector_slow::<E, Q>(
             root,
             selector_list,
             results,
             &mut matching_context,
         );