diff --git a/content/media/webaudio/AudioBuffer.cpp b/content/media/webaudio/AudioBuffer.cpp
index 04d6136224f..fc2c90b2f49 100644
--- a/content/media/webaudio/AudioBuffer.cpp
+++ b/content/media/webaudio/AudioBuffer.cpp
@@ -226,7 +226,7 @@ StealJSArrayDataIntoThreadSharedFloatArrayBufferList(JSContext* aJSContext,
                           ? (uint8_t*) JS_StealArrayBufferContents(aJSContext, arrayBuffer)
                           : nullptr;
     if (stolenData) {
-      result->SetData(i, stolenData, reinterpret_cast<float*>(stolenData));
+      result->SetData(i, stolenData, js_free, reinterpret_cast<float*>(stolenData));
     } else {
       return nullptr;
     }
diff --git a/content/media/webaudio/AudioNodeEngine.h b/content/media/webaudio/AudioNodeEngine.h
index 626d52dd834..2d30737ab1f 100644
--- a/content/media/webaudio/AudioNodeEngine.h
+++ b/content/media/webaudio/AudioNodeEngine.h
@@ -38,12 +38,16 @@ public:
   }
 
   struct Storage {
-    Storage()
-    {
-      mDataToFree = nullptr;
-      mSampleData = nullptr;
+    Storage() :
+      mDataToFree(nullptr),
+      mFree(nullptr),
+      mSampleData(nullptr)
+    {}
+    ~Storage() {
+      if (mFree) {
+        mFree(mDataToFree);
+      } else { MOZ_ASSERT(!mDataToFree); }
     }
-    ~Storage() { free(mDataToFree); }
     size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
     {
       // NB: mSampleData might not be owned, if it is it just points to
@@ -51,6 +55,7 @@ public:
       return aMallocSizeOf(mDataToFree);
     }
     void* mDataToFree;
+    void (*mFree)(void*);
     const float* mSampleData;
   };
 
@@ -67,11 +72,17 @@ public:
    * Call this only during initialization, before the object is handed to
    * any other thread.
    */
-  void SetData(uint32_t aIndex, void* aDataToFree, const float* aData)
+  void SetData(uint32_t aIndex, void* aDataToFree, void (*aFreeFunc)(void*), const float* aData)
   {
     Storage* s = &mContents[aIndex];
-    free(s->mDataToFree);
+    if (s->mFree) {
+      s->mFree(s->mDataToFree);
+    } else {
+      MOZ_ASSERT(!s->mDataToFree);
+    }
+
     s->mDataToFree = aDataToFree;
+    s->mFree = aFreeFunc;
     s->mSampleData = aData;
   }
 
diff --git a/content/media/webaudio/ConvolverNode.cpp b/content/media/webaudio/ConvolverNode.cpp
index 1f14c555e4c..9937f3e6bb7 100644
--- a/content/media/webaudio/ConvolverNode.cpp
+++ b/content/media/webaudio/ConvolverNode.cpp
@@ -258,7 +258,7 @@ ConvolverNode::SetBuffer(JSContext* aCx, AudioBuffer* aBuffer, ErrorResult& aRv)
       for (uint32_t i = 0; i < data->GetChannels(); ++i) {
         PodCopy(channelData + length * i, data->GetData(i), mBuffer->Length());
         PodZero(channelData + length * i + mBuffer->Length(), WEBAUDIO_BLOCK_SIZE - mBuffer->Length());
-        paddedBuffer->SetData(i, (i == 0) ? channelData : nullptr, channelData);
+        paddedBuffer->SetData(i, (i == 0) ? channelData : nullptr, free, channelData);
       }
       data = paddedBuffer;
     }
diff --git a/content/media/webaudio/PeriodicWave.cpp b/content/media/webaudio/PeriodicWave.cpp
index 1d0e9a74a12..7a86f39cd4d 100644
--- a/content/media/webaudio/PeriodicWave.cpp
+++ b/content/media/webaudio/PeriodicWave.cpp
@@ -38,9 +38,9 @@ PeriodicWave::PeriodicWave(AudioContext* aContext,
     return;
   }
   PodCopy(buffer, aRealData, aLength);
-  mCoefficients->SetData(0, buffer, buffer);
+  mCoefficients->SetData(0, buffer, free, buffer);
   PodCopy(buffer+aLength, aImagData, aLength);
-  mCoefficients->SetData(1, nullptr, buffer+aLength);
+  mCoefficients->SetData(1, nullptr, free, buffer+aLength);
 }
 
 size_t