diff --git a/av/audio/stream.pyi b/av/audio/stream.pyi
index d079550e8..c85f15787 100644
--- a/av/audio/stream.pyi
+++ b/av/audio/stream.pyi
@@ -1,3 +1,5 @@
+from typing import Literal
+
 from av.packet import Packet
 from av.stream import Stream
 
@@ -6,7 +8,7 @@ from .frame import AudioFrame
 
 class AudioStream(Stream):
     format: AudioFormat
-    type = "audio"
+    type: Literal["audio"]
 
     def encode(self, frame: AudioFrame | None = None) -> list[Packet]: ...
     def decode(self, packet: Packet | None = None) -> list[AudioFrame]: ...