diff --git a/layout/style/nsCSSRuleProcessor.cpp b/layout/style/nsCSSRuleProcessor.cpp
index c8f888e7a1..3644e3e45b 100644
--- a/layout/style/nsCSSRuleProcessor.cpp
+++ b/layout/style/nsCSSRuleProcessor.cpp
@@ -1960,15 +1960,15 @@ static bool SelectorMatches(Element* aElement,
           // selector.
            
           // We match automatically if GetParent() and GetShadowRoot() have 
-          // the same result. Without special casing this ahead of all other 
-          // selector matching, it fails. Have not determined the cause.
-
-          if (aElement->GetParent() == aElement->GetShadowRoot()) {
+          // the same result iff our selector list is empty. Without special
+          // casing this ahead of all other selector matching, it fails.
+          // Have not determined the cause.
+          if (!pseudoClass->u.mSelectorList &&
+              aElement->GetParent() == aElement->GetShadowRoot()) {
             break;
           }
 
           // Match if any selector in the argument list matches.
-
           NodeMatchContext nodeContext(EventStates(),
                                nsCSSRuleProcessor::IsLink(aElement));
           if (SelectorListMatches(aElement,