diff --git a/syncplay/constants.py b/syncplay/constants.py
index adb63ea..9ab1ada 100644
--- a/syncplay/constants.py
+++ b/syncplay/constants.py
@@ -134,7 +134,7 @@ USERLIST_GUI_USERNAME_OFFSET = 21 # Pixels
 
 MPLAYER_SLAVE_ARGS = ['-slave', '--hr-seek=always', '-nomsgcolor', '-msglevel', 'all=1:global=4:cplayer=4', '-af', 'scaletempo']
 # --quiet works with both mpv 0.2 and 0.3
-MPV_SLAVE_ARGS = ['--force-window', '--idle', '--hr-seek=always', '--quiet', '--keep-open', '--af=scaletempo', '--input-terminal=no', '--input-file=/dev/stdin']
+MPV_SLAVE_ARGS = ['--force-window', '--idle', '--hr-seek=always', '--quiet', '--keep-open', '--af-add=scaletempo', '--input-terminal=no', '--input-file=/dev/stdin']
 MPV_SLAVE_ARGS_NEW = ['--term-playing-msg=<SyncplayUpdateFile>\nANS_filename=${filename}\nANS_length=${=length}\nANS_path=${path}\n</SyncplayUpdateFile>', '--terminal=yes']
 MPV_NEW_VERSION = False
 VLC_SLAVE_ARGS = ['--extraintf=luaintf', '--lua-intf=syncplay', '--no-quiet', '--no-input-fast-seek',