diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Document.h b/Userland/Libraries/LibVideo/Containers/Matroska/Document.h
index 861f230ba00..5c1dc652834 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Document.h
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Document.h
@@ -8,7 +8,7 @@
 
 #include <AK/ByteBuffer.h>
 #include <AK/ByteString.h>
-#include <AK/DeprecatedFlyString.h>
+#include <AK/FlyString.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/Time.h>
@@ -115,10 +115,10 @@ public:
     void set_track_uid(u64 track_uid) { m_track_uid = track_uid; }
     TrackType track_type() const { return m_track_type; }
     void set_track_type(TrackType track_type) { m_track_type = track_type; }
-    DeprecatedFlyString language() const { return m_language; }
-    void set_language(DeprecatedFlyString const& language) { m_language = language; }
-    DeprecatedFlyString codec_id() const { return m_codec_id; }
-    void set_codec_id(DeprecatedFlyString const& codec_id) { m_codec_id = codec_id; }
+    FlyString language() const { return m_language; }
+    void set_language(FlyString const& language) { m_language = language; }
+    FlyString codec_id() const { return m_codec_id; }
+    void set_codec_id(FlyString const& codec_id) { m_codec_id = codec_id; }
     double timestamp_scale() const { return m_timestamp_scale; }
     void set_timestamp_scale(double timestamp_scale) { m_timestamp_scale = timestamp_scale; }
     u64 codec_delay() const { return m_codec_delay; }
@@ -144,8 +144,8 @@ private:
     u64 m_track_number { 0 };
     u64 m_track_uid { 0 };
     TrackType m_track_type { Invalid };
-    DeprecatedFlyString m_language = "eng";
-    DeprecatedFlyString m_codec_id;
+    FlyString m_language = "eng"_fly_string;
+    FlyString m_codec_id;
     double m_timestamp_scale { 1 };
     u64 m_codec_delay { 0 };
     u64 m_timestamp_offset { 0 };
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
index f8befa7eed3..c646457b500 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.cpp
@@ -71,7 +71,7 @@ DecoderErrorOr<MatroskaDemuxer::TrackStatus*> MatroskaDemuxer::get_track_status(
     return &m_track_statuses.get(track).release_value();
 }
 
-CodecID MatroskaDemuxer::get_codec_id_for_string(DeprecatedFlyString const& codec_id)
+CodecID MatroskaDemuxer::get_codec_id_for_string(FlyString const& codec_id)
 {
     dbgln_if(MATROSKA_DEBUG, "Codec ID: {}", codec_id);
     if (codec_id == "V_VP8")
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.h b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.h
index 2a2c0eb9359..4caa6351600 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.h
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/MatroskaDemuxer.h
@@ -46,7 +46,7 @@ private:
     };
 
     DecoderErrorOr<TrackStatus*> get_track_status(Track track);
-    CodecID get_codec_id_for_string(DeprecatedFlyString const& codec_id);
+    CodecID get_codec_id_for_string(FlyString const& codec_id);
 
     Reader m_reader;
 
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
index d5ac59420dd..4a7de8357fb 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
@@ -468,11 +468,11 @@ static DecoderErrorOr<TrackEntry> parse_track_entry(Streamer& streamer)
             dbgln_if(MATROSKA_TRACE_DEBUG, "Read TrackType attribute: {}", to_underlying(track_entry.track_type()));
             break;
         case TRACK_LANGUAGE_ID:
-            track_entry.set_language(TRY_READ(streamer.read_string()));
+            track_entry.set_language(DECODER_TRY_ALLOC(FlyString::from_utf8(TRY_READ(streamer.read_string()).view())));
             dbgln_if(MATROSKA_TRACE_DEBUG, "Read Track's Language attribute: {}", track_entry.language());
             break;
         case TRACK_CODEC_ID:
-            track_entry.set_codec_id(TRY_READ(streamer.read_string()));
+            track_entry.set_codec_id(DECODER_TRY_ALLOC(FlyString::from_utf8(TRY_READ(streamer.read_string()).view())));
             dbgln_if(MATROSKA_TRACE_DEBUG, "Read Track's CodecID attribute: {}", track_entry.codec_id());
             break;
         case TRACK_TIMESTAMP_SCALE_ID:
diff --git a/Userland/Utilities/matroska.cpp b/Userland/Utilities/matroska.cpp
index 611cfb9af07..9be03e5c295 100644
--- a/Userland/Utilities/matroska.cpp
+++ b/Userland/Utilities/matroska.cpp
@@ -52,8 +52,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         outln("\tTrack #{} with TrackID {}", track_entry.track_number(), track_entry.track_uid());
         outln("\tTrack has TrackType {}", static_cast<u8>(track_entry.track_type()));
-        outln("\tTrack has Language \"{}\"", track_entry.language().characters());
-        outln("\tTrack has CodecID \"{}\"", track_entry.codec_id().characters());
+        outln("\tTrack has Language \"{}\"", track_entry.language());
+        outln("\tTrack has CodecID \"{}\"", track_entry.codec_id());
         outln("\tTrack has TrackTimestampScale {}", track_entry.timestamp_scale());
         outln("\tTrack has CodecDelay {}", track_entry.codec_delay());