--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -758,16 +758,21 @@ MediaDecoder::MetadataLoaded(UniquePtr<M
   // Invalidate() will end up calling GetOwner()->UpdateMediaSize with the last
   // dimensions retrieved from the video frame container. The video frame
   // container contains more up to date dimensions than aInfo.
   // So we call Invalidate() after calling GetOwner()->MetadataLoaded to ensure
   // the media element has the latest dimensions.
   Invalidate();
 
   EnsureTelemetryReported();
+
+  // The duration is no longer infinite when we get one from the metadata.
+  if (mInfo->mMetadataDuration && IsInfinite()) {
+    SetInfinite(false);
+  }
 }
 
 void
 MediaDecoder::EnsureTelemetryReported()
 {
   MOZ_ASSERT(NS_IsMainThread());
 
   if (mTelemetryReported || !mInfo) {