--- a/dom/media/mediasource/MediaSource.cpp
+++ b/dom/media/mediasource/MediaSource.cpp
@@ -364,57 +364,49 @@ MediaSource::Enabled(JSContext* cx, JSOb
 
 void
 MediaSource::SetLiveSeekableRange(double aStart, double aEnd, ErrorResult& aRv)
 {
   MOZ_ASSERT(NS_IsMainThread());
 
   // 1. If the readyState attribute is not "open" then throw an InvalidStateError
   // exception and abort these steps.
-  // 2. If the updating attribute equals true on any SourceBuffer in
-  // sourceBuffers, then throw an InvalidStateError exception and abort these
-  // steps.
-  if (mReadyState != MediaSourceReadyState::Open ||
-      mSourceBuffers->AnyUpdating()) {
+  if (mReadyState != MediaSourceReadyState::Open) {
     aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
   }
 
-  // 3. If start is negative or greater than end, then throw a TypeError
+  // 2. If start is negative or greater than end, then throw a TypeError
   // exception and abort these steps.
   if (aStart < 0 || aStart > aEnd) {
     aRv.Throw(NS_ERROR_DOM_TYPE_ERR);
     return;
   }
 
-  // 4. Set live seekable range to be a new normalized TimeRanges object
+  // 3. Set live seekable range to be a new normalized TimeRanges object
   // containing a single range whose start position is start and end position is
   // end.
   mLiveSeekableRange =
     Some(media::TimeInterval(media::TimeUnit::FromSeconds(aStart),
                              media::TimeUnit::FromSeconds(aEnd)));
 }
 
 void
 MediaSource::ClearLiveSeekableRange(ErrorResult& aRv)
 {
   MOZ_ASSERT(NS_IsMainThread());
 
   // 1. If the readyState attribute is not "open" then throw an InvalidStateError
   // exception and abort these steps.
-  // 2. If the updating attribute equals true on any SourceBuffer in
-  // sourceBuffers, then throw an InvalidStateError exception and abort these
-  // steps.
-  if (mReadyState != MediaSourceReadyState::Open ||
-      mSourceBuffers->AnyUpdating()) {
+  if (mReadyState != MediaSourceReadyState::Open) {
     aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
   }
 
-  // 3. If live seekable range contains a range, then set live seekable range to
+  // 2. If live seekable range contains a range, then set live seekable range to
   // be a new empty TimeRanges object.
   mLiveSeekableRange.reset();
 }
 
 bool
 MediaSource::Attach(MediaSourceDecoder* aDecoder)
 {
   MOZ_ASSERT(NS_IsMainThread());