diff --git a/content/media/webaudio/AudioProcessingEvent.cpp b/content/media/webaudio/AudioProcessingEvent.cpp
index 4cb44d9382e8..01962fd09b48 100644
--- a/content/media/webaudio/AudioProcessingEvent.cpp
+++ b/content/media/webaudio/AudioProcessingEvent.cpp
@@ -37,23 +37,30 @@ AudioProcessingEvent::WrapObject(JSContext* aCx)
   return AudioProcessingEventBinding::Wrap(aCx, this);
 }
 
-void
-AudioProcessingEvent::LazilyCreateBuffer(nsRefPtr<AudioBuffer>& aBuffer,
-                                         uint32_t aNumberOfChannels)
+already_AddRefed<AudioBuffer>
+AudioProcessingEvent::LazilyCreateBuffer(uint32_t aNumberOfChannels,
+                                         ErrorResult& aRv)
 {
   // We need the global for the context so that we can enter its compartment.
   JSObject* global = mNode->Context()->GetGlobalJSObject();
   if (NS_WARN_IF(!global)) {
-    return;
+    aRv.Throw(NS_ERROR_UNEXPECTED);
+    return nullptr;
   }
 
   AutoJSAPI jsapi;
   JSContext* cx = jsapi.cx();
   JSAutoCompartment ac(cx, global);
 
-  aBuffer = new AudioBuffer(mNode->Context(), mNode->BufferSize(),
-                            mNode->Context()->SampleRate());
-  aBuffer->InitializeBuffers(aNumberOfChannels, cx);
+  nsRefPtr<AudioBuffer> buffer =
+    new AudioBuffer(mNode->Context(), mNode->BufferSize(),
+                    mNode->Context()->SampleRate());
+  if (!buffer->InitializeBuffers(aNumberOfChannels, cx)) {
+    aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+    return nullptr;
+  }
+
+  return buffer.forget();
 }
 
 }
diff --git a/content/media/webaudio/AudioProcessingEvent.h b/content/media/webaudio/AudioProcessingEvent.h
index e32e2ebd54c8..49a333cb19ae 100644
--- a/content/media/webaudio/AudioProcessingEvent.h
+++ b/content/media/webaudio/AudioProcessingEvent.h
@@ -42,18 +42,18 @@ public:
     return mPlaybackTime;
   }
 
-  AudioBuffer* InputBuffer()
+  AudioBuffer* GetInputBuffer(ErrorResult& aRv)
   {
     if (!mInputBuffer) {
-      LazilyCreateBuffer(mInputBuffer, mNumberOfInputChannels);
+      mInputBuffer = LazilyCreateBuffer(mNumberOfInputChannels, aRv);
     }
     return mInputBuffer;
   }
 
-  AudioBuffer* OutputBuffer()
+  AudioBuffer* GetOutputBuffer(ErrorResult& aRv)
   {
     if (!mOutputBuffer) {
-      LazilyCreateBuffer(mOutputBuffer, mNode->NumberOfOutputChannels());
+      mOutputBuffer = LazilyCreateBuffer(mNode->NumberOfOutputChannels(), aRv);
     }
     return mOutputBuffer;
   }
@@ -64,8 +64,8 @@ public:
   }
 
 private:
-  void LazilyCreateBuffer(nsRefPtr<AudioBuffer>& aBuffer,
-                          uint32_t aNumberOfChannels);
+  already_AddRefed<AudioBuffer>
+  LazilyCreateBuffer(uint32_t aNumberOfChannels, ErrorResult& rv);
 
 private:
   double mPlaybackTime;
diff --git a/content/media/webaudio/ScriptProcessorNode.cpp b/content/media/webaudio/ScriptProcessorNode.cpp
index 57b6d447ee58..ea441c7e4344 100644
--- a/content/media/webaudio/ScriptProcessorNode.cpp
+++ b/content/media/webaudio/ScriptProcessorNode.cpp
@@ -438,10 +438,18 @@ private:
                          mPlaybackTime);
         node->DispatchTrustedEvent(event);
 
-        // Steal the output buffers
+        // Steal the output buffers if they have been set.
+        // Don't create a buffer if it hasn't been used to return output;
+        // FinishProducingOutputBuffer() will optimize output = null.
+        // GetThreadSharedChannelsForRate() may also return null after OOM.
         nsRefPtr<ThreadSharedFloatArrayBufferList> output;
         if (event->HasOutputBuffer()) {
-          output = event->OutputBuffer()->GetThreadSharedChannelsForRate(cx);
+          ErrorResult rv;
+          AudioBuffer* buffer = event->GetOutputBuffer(rv);
+          // HasOutputBuffer() returning true means that GetOutputBuffer()
+          // will not fail.
+          MOZ_ASSERT(!rv.Failed());
+          output = buffer->GetThreadSharedChannelsForRate(cx);
         }
 
         // Append it to our output buffer queue
diff --git a/dom/webidl/AudioProcessingEvent.webidl b/dom/webidl/AudioProcessingEvent.webidl
index 9d061499e091..17ee321fb193 100644
--- a/dom/webidl/AudioProcessingEvent.webidl
+++ b/dom/webidl/AudioProcessingEvent.webidl
@@ -12,9 +12,12 @@
 
 interface AudioProcessingEvent : Event {
 
-    readonly attribute double playbackTime;
-    readonly attribute AudioBuffer inputBuffer;
-    readonly attribute AudioBuffer outputBuffer;
+  readonly attribute double playbackTime;
+
+  [Throws]
+  readonly attribute AudioBuffer inputBuffer;
+  [Throws]
+  readonly attribute AudioBuffer outputBuffer;
 
 };