--- a/layout/style/ServoCSSRuleList.cpp
+++ b/layout/style/ServoCSSRuleList.cpp
@@ -37,16 +37,23 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(Se
   tmp->DropAllRules();
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END_INHERITED(dom::CSSRuleList)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(ServoCSSRuleList,
                                                   dom::CSSRuleList)
   tmp->EnumerateInstantiatedRules([&](css::Rule* aRule) {
     if (!aRule->IsCCLeaf()) {
       NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mRules[i]");
       cb.NoteXPCOMChild(aRule);
+      // Note about @font-face rule again, since there is an indirect
+      // owning edge through Servo's struct that FontFaceRule in Servo
+      // owns a Gecko nsCSSFontFaceRule object.
+      if (aRule->Type() == nsIDOMCSSRule::FONT_FACE_RULE) {
+        NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mRawRules[i]");
+        cb.NoteXPCOMChild(aRule);
+      }
     }
   });
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 void
 ServoCSSRuleList::SetParentRule(css::GroupRule* aParentRule)
 {
   mParentRule = aParentRule;
@@ -134,16 +141,17 @@ DropRule(already_AddRefed<css::Rule> aRu
 
 void
 ServoCSSRuleList::DropAllRules()
 {
   EnumerateInstantiatedRules([](css::Rule* rule) {
     DropRule(already_AddRefed<css::Rule>(rule));
   });
   mRules.Clear();
+  mRawRules = nullptr;
 }
 
 void
 ServoCSSRuleList::DropReference()
 {
   mStyleSheet = nullptr;
   mParentRule = nullptr;
   DropAllRules();