--- a/dom/media/webaudio/AudioBuffer.cpp
+++ b/dom/media/webaudio/AudioBuffer.cpp
@@ -326,17 +326,17 @@ AudioBuffer::CopyFromChannel(const Float
 {
   aDestination.ComputeLengthAndData();
 
   uint32_t length = aDestination.Length();
   CheckedInt<uint32_t> end = aStartInChannel;
   end += length;
   if (aChannelNumber >= NumberOfChannels() ||
       !end.isValid() || end.value() > Length()) {
-    aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
+    aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
     return;
   }
 
   JS::AutoCheckCannotGC nogc;
   JSObject* channelArray = mJSChannels[aChannelNumber];
   if (channelArray) {
     if (JS_GetTypedArrayLength(channelArray) != Length()) {
       // The array's buffer was detached.
@@ -370,17 +370,17 @@ AudioBuffer::CopyToChannel(JSContext* aJ
 {
   aSource.ComputeLengthAndData();
 
   uint32_t length = aSource.Length();
   CheckedInt<uint32_t> end = aStartInChannel;
   end += length;
   if (aChannelNumber >= NumberOfChannels() ||
       !end.isValid() || end.value() > Length()) {
-    aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
+    aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
     return;
   }
 
   if (!RestoreJSChannelData(aJSContext)) {
     aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
     return;
   }
 
@@ -401,17 +401,17 @@ AudioBuffer::CopyToChannel(JSContext* aJ
 }
 
 void
 AudioBuffer::GetChannelData(JSContext* aJSContext, uint32_t aChannel,
                             JS::MutableHandle<JSObject*> aRetval,
                             ErrorResult& aRv)
 {
   if (aChannel >= NumberOfChannels()) {
-    aRv.Throw(NS_ERROR_DOM_NOT_SUPPORTED_ERR);
+    aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
     return;
   }
 
   if (!RestoreJSChannelData(aJSContext)) {
     aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
     return;
   }