diff --git a/android/app/src/main/java/com/audiobookshelf/app/data/AudioTrack.kt b/android/app/src/main/java/com/audiobookshelf/app/data/AudioTrack.kt
index 086175d3..a7dd1b86 100644
--- a/android/app/src/main/java/com/audiobookshelf/app/data/AudioTrack.kt
+++ b/android/app/src/main/java/com/audiobookshelf/app/data/AudioTrack.kt
@@ -10,7 +10,7 @@ data class AudioTrack(
         var duration: Double,
         var title: String,
         var contentUrl: String,
-        var mimeType: String,
+        var mimeType: String?,
         var metadata: FileMetadata?,
         var isLocal: Boolean,
         var localFileId: String?,
diff --git a/android/app/src/main/java/com/audiobookshelf/app/data/PlaybackSession.kt b/android/app/src/main/java/com/audiobookshelf/app/data/PlaybackSession.kt
index 2a4b8b30..7a2ea432 100644
--- a/android/app/src/main/java/com/audiobookshelf/app/data/PlaybackSession.kt
+++ b/android/app/src/main/java/com/audiobookshelf/app/data/PlaybackSession.kt
@@ -332,7 +332,7 @@ class PlaybackSession(
             MediaInfo.Builder(mediaUri.toString())
                     .apply {
                       setContentUrl(mediaUri.toString())
-                      setContentType(audioTrack.mimeType)
+                      setContentType(audioTrack.mimeType ?: "")
                       setMetadata(castMetadata)
                       setStreamType(MediaInfo.STREAM_TYPE_BUFFERED)
                     }