diff --git a/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs b/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
index d63ea7502d..72986818aa 100644
--- a/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
+++ b/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
@@ -20,6 +20,7 @@ using Jellyfin.Extensions;
 using MediaBrowser.Common.Configuration;
 using MediaBrowser.Controller.Extensions;
 using MediaBrowser.Controller.IO;
+using MediaBrowser.Controller.Streaming;
 using MediaBrowser.Model.Configuration;
 using MediaBrowser.Model.Dlna;
 using MediaBrowser.Model.Dto;
@@ -7484,7 +7485,8 @@ namespace MediaBrowser.Controller.MediaEncoding
             {
                 // Use fragmented MP4 for adaptive streaming (HLS/DASH with segments)
                 // Use faststart for progressive downloads (better seeking and metadata)
-                if (!string.IsNullOrEmpty(state.Request.SegmentContainer))
+                var streamingRequest = state.BaseRequest as StreamingRequestDto;
+                if (streamingRequest?.SegmentContainer is not null)
                 {
                     // Fragmented MP4 for HLS/DASH
                     format = " -f mp4 -movflags frag_keyframe+empty_moov+delay_moov";