diff --git a/dom/media/webaudio/AudioNodeEngine.cpp b/dom/media/webaudio/AudioNodeEngine.cpp
index eb80304c5be..1ff03bbfca7 100644
--- a/dom/media/webaudio/AudioNodeEngine.cpp
+++ b/dom/media/webaudio/AudioNodeEngine.cpp
@@ -29,7 +29,7 @@ ThreadSharedFloatArrayBufferList::Create(uint32_t aChannelCount, size_t aLength,
       new ThreadSharedFloatArrayBufferList(aChannelCount);
 
   for (uint32_t i = 0; i < aChannelCount; ++i) {
-    float* channelData = js_pod_malloc<float>(aLength);
+    float* channelData = js_pod_calloc<float>(aLength);
     if (!channelData) {
       return nullptr;
     }
diff --git a/dom/media/webaudio/AudioNodeEngine.h b/dom/media/webaudio/AudioNodeEngine.h
index de7785c086b..4f5af79362c 100644
--- a/dom/media/webaudio/AudioNodeEngine.h
+++ b/dom/media/webaudio/AudioNodeEngine.h
@@ -42,8 +42,8 @@ class ThreadSharedFloatArrayBufferList final : public ThreadSharedObject {
   }
   /**
    * Create with buffers suitable for transfer to
-   * JS::NewArrayBufferWithContents().  The buffer contents are uninitialized
-   * and so should be set using GetDataForWrite().
+   * JS::NewArrayBufferWithContents().  The buffer contents are
+   * zero-initialised; callers should set them using GetDataForWrite().
    */
   static already_AddRefed<ThreadSharedFloatArrayBufferList> Create(
       uint32_t aChannelCount, size_t aLength, const mozilla::fallible_t&);