diff --git a/src/libguac/audio.c b/src/libguac/audio.c
index 84e4c334..1f32d6d0 100644
--- a/src/libguac/audio.c
+++ b/src/libguac/audio.c
@@ -136,7 +136,7 @@ void guac_audio_stream_end(guac_audio_stream* audio) {
 
     /* Send audio */
     guac_protocol_send_audio(audio->client->socket, audio->stream,
-            audio->encoder->mimetype, duration);
+            audio->stream->index, audio->encoder->mimetype, duration);
 
     guac_protocol_send_blob(audio->client->socket, audio->stream,
             audio->encoded_data, audio->encoded_data_used);
diff --git a/src/libguac/guacamole/protocol.h b/src/libguac/guacamole/protocol.h
index cad8e90c..dcc5045d 100644
--- a/src/libguac/guacamole/protocol.h
+++ b/src/libguac/guacamole/protocol.h
@@ -282,12 +282,13 @@ int guac_protocol_send_sync(guac_socket* socket, guac_timestamp timestamp);
  *
  * @param socket The guac_socket connection to use.
  * @param stream The stream to use.
+ * @param channel The index of the audio channel to use.
  * @param mimetype The mimetype of the data being sent.
  * @param duration The duration of the sound being sent, in milliseconds.
  * @return Zero on success, non-zero on error.
  */
 int guac_protocol_send_audio(guac_socket* socket, const guac_stream* stream,
-        const char* mimetype, double duration);
+        int channel, const char* mimetype, double duration);
 
 /**
  * Sends a file instruction over the given guac_socket connection.
diff --git a/src/libguac/protocol.c b/src/libguac/protocol.c
index cba5980c..2cc2c2fb 100644
--- a/src/libguac/protocol.c
+++ b/src/libguac/protocol.c
@@ -417,7 +417,7 @@ int guac_protocol_send_arc(guac_socket* socket, const guac_layer* layer,
 }
 
 int guac_protocol_send_audio(guac_socket* socket, const guac_stream* stream,
-        const char* mimetype, double duration) {
+        int channel, const char* mimetype, double duration) {
 
     int ret_val;
 
@@ -426,6 +426,8 @@ int guac_protocol_send_audio(guac_socket* socket, const guac_stream* stream,
            guac_socket_write_string(socket, "5.audio,")
         || __guac_socket_write_length_int(socket, stream->index)
         || guac_socket_write_string(socket, ",")
+        || __guac_socket_write_length_int(socket, channel)
+        || guac_socket_write_string(socket, ",")
         || __guac_socket_write_length_string(socket, mimetype)
         || guac_socket_write_string(socket, ",")
         || __guac_socket_write_length_double(socket, duration)