diff --git a/bin/muxsa-pngaac2mp4 b/bin/muxsa-pngaac2mp4
index 6eb470d..4fd1f4a 100755
--- a/bin/muxsa-pngaac2mp4
+++ b/bin/muxsa-pngaac2mp4
@@ -127,7 +127,7 @@ esac
 # no "quotes" around the $..._OPTs on purpose
 set -ex
 ffmpeg -f concat -safe 0 -i "$SLIDES_IN" $AUDIO_SOURCE_OPTS "$AUDIO_IN" \
-    -vsync cfr -vf fps=25 \
+    -fps_mode cfr -vf fps=25 \
     -c:v libx264 -preset slow -tune stillimage -crf 23 -pix_fmt yuv420p \
     $AUDIO_CODER_OPTS \
     -movflags +faststart -brand mp42 "$VIDEO_OUT"