--- a/dom/media/webaudio/OscillatorNode.cpp
+++ b/dom/media/webaudio/OscillatorNode.cpp
@@ -102,17 +102,16 @@ public:
     switch (aIndex) {
       case TYPE:
         // Set the new type.
         mType = static_cast<OscillatorType>(aParam);
         if (mType == OscillatorType::Sine) {
           // Forget any previous custom data.
           mCustomLength = 0;
           mCustomDisableNormalization = false;
-          mCustom = nullptr;
           mPeriodicWave = nullptr;
           mRecomputeParameters = true;
         }
         switch (mType) {
           case OscillatorType::Sine:
             mPhase = 0.0;
             break;
           case OscillatorType::Square:
@@ -139,22 +138,22 @@ public:
         NS_ERROR("Bad OscillatorNodeEngine Int32Parameter.");
     }
     // End index switch.
   }
 
   void SetBuffer(already_AddRefed<ThreadSharedFloatArrayBufferList> aBuffer) override
   {
     MOZ_ASSERT(mCustomLength, "Custom buffer sent before length");
-    mCustom = aBuffer;
-    MOZ_ASSERT(mCustom->GetChannels() == 2,
+    RefPtr<ThreadSharedFloatArrayBufferList> custom = aBuffer;
+    MOZ_ASSERT(custom->GetChannels() == 2,
                "PeriodicWave should have sent two channels");
     mPeriodicWave = WebCore::PeriodicWave::create(mSource->SampleRate(),
-                                                  mCustom->GetData(0),
-                                                  mCustom->GetData(1),
+                                                  custom->GetData(0),
+                                                  custom->GetData(1),
                                                   mCustomLength,
                                                   mCustomDisableNormalization);
   }
 
   void IncrementPhase()
   {
     const float twoPiFloat = float(2 * M_PI);
     mPhase += mPhaseIncrement;
@@ -368,20 +367,16 @@ public:
     size_t amount = AudioNodeEngine::SizeOfExcludingThis(aMallocSizeOf);
 
     // Not owned:
     // - mSource
     // - mDestination
     // - mFrequency (internal ref owned by node)
     // - mDetune (internal ref owned by node)
 
-    if (mCustom) {
-      amount += mCustom->SizeOfIncludingThis(aMallocSizeOf);
-    }
-
     if (mPeriodicWave) {
       amount += mPeriodicWave->sizeOfIncludingThis(aMallocSizeOf);
     }
 
     return amount;
   }
 
   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
@@ -396,17 +391,16 @@ public:
   StreamTime mStop;
   AudioParamTimeline mFrequency;
   AudioParamTimeline mDetune;
   OscillatorType mType;
   float mPhase;
   float mFinalFrequency;
   float mPhaseIncrement;
   bool mRecomputeParameters;
-  RefPtr<ThreadSharedFloatArrayBufferList> mCustom;
   RefPtr<BasicWaveFormCache> mBasicWaveFormCache;
   uint32_t mCustomLength;
   bool mCustomDisableNormalization;
   RefPtr<WebCore::PeriodicWave> mPeriodicWave;
 };
 
 OscillatorNode::OscillatorNode(AudioContext* aContext)
   : AudioScheduledSourceNode(aContext,