diff --git a/libraries/extractor/src/main/java/androidx/media3/extractor/mkv/MatroskaExtractor.java b/libraries/extractor/src/main/java/androidx/media3/extractor/mkv/MatroskaExtractor.java
index ebff39266e..405951074c 100644
--- a/libraries/extractor/src/main/java/androidx/media3/extractor/mkv/MatroskaExtractor.java
+++ b/libraries/extractor/src/main/java/androidx/media3/extractor/mkv/MatroskaExtractor.java
@@ -2156,9 +2156,11 @@ public class MatroskaExtractor implements Extractor {
           break;
         case CODEC_ID_VP9:
           mimeType = MimeTypes.VIDEO_VP9;
+          initializationData = codecPrivate == null ? null : ImmutableList.of(codecPrivate);
           break;
         case CODEC_ID_AV1:
           mimeType = MimeTypes.VIDEO_AV1;
+          initializationData = codecPrivate == null ? null : ImmutableList.of(codecPrivate);
           break;
         case CODEC_ID_MPEG2:
           mimeType = MimeTypes.VIDEO_MPEG2;