--- a/dom/animation/KeyframeEffect.cpp
+++ b/dom/animation/KeyframeEffect.cpp
@@ -57,17 +57,18 @@ GetComputedTimingDictionary(const Comput
   }
 }
 
 namespace dom {
 
 NS_IMPL_CYCLE_COLLECTION_INHERITED(KeyframeEffectReadOnly,
                                    AnimationEffectReadOnly,
                                    mTarget,
-                                   mAnimation)
+                                   mAnimation,
+                                   mTiming)
 
 NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(KeyframeEffectReadOnly,
                                                AnimationEffectReadOnly)
 NS_IMPL_CYCLE_COLLECTION_TRACE_END
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(KeyframeEffectReadOnly)
 NS_INTERFACE_MAP_END_INHERITING(AnimationEffectReadOnly)
 
@@ -87,17 +88,17 @@ KeyframeEffectReadOnly::KeyframeEffectRe
 
 KeyframeEffectReadOnly::KeyframeEffectReadOnly(
   nsIDocument* aDocument,
   Element* aTarget,
   CSSPseudoElementType aPseudoType,
   AnimationEffectTimingReadOnly* aTiming)
   : AnimationEffectReadOnly(aDocument)
   , mTarget(aTarget)
-  , mTiming(*aTiming)
+  , mTiming(aTiming)
   , mPseudoType(aPseudoType)
   , mInEffectOnLastAnimationTimingUpdate(false)
 {
   MOZ_ASSERT(aTiming);
   MOZ_ASSERT(aTarget, "null animation target is not yet supported");
 }
 
 JSObject*
@@ -1398,13 +1399,17 @@ void KeyframeEffect::NotifySpecifiedTimi
                        EffectCompositor::RestyleType::Layer,
                        mAnimation->CascadeLevel());
     }
   }
 }
 
 KeyframeEffect::~KeyframeEffect()
 {
-  mTiming->Unlink();
+  // mTiming is cycle collected, so we have to do null check first even though
+  // mTiming shouldn't be null during the lifetime of KeyframeEffect.
+  if (mTiming) {
+    mTiming->Unlink();
+  }
 }
 
 } // namespace dom
 } // namespace mozilla

--- a/dom/animation/KeyframeEffect.h
+++ b/dom/animation/KeyframeEffect.h
@@ -367,17 +367,17 @@ protected:
   // As a result, we need to make sure this gets called whenever anything
   // changes with regards to this effects's timing including changes to the
   // owning Animation's timing.
   void UpdateTargetRegistration();
 
   nsCOMPtr<Element> mTarget;
   RefPtr<Animation> mAnimation;
 
-  OwningNonNull<AnimationEffectTimingReadOnly> mTiming;
+  RefPtr<AnimationEffectTimingReadOnly> mTiming;
   CSSPseudoElementType mPseudoType;
 
   // The specified keyframes.
   nsTArray<Keyframe>          mFrames;
 
   // A set of per-property value arrays, derived from |mFrames|.
   nsTArray<AnimationProperty> mProperties;