diff --git a/video/out/vo.c b/video/out/vo.c
index 94dcabf00e..1db8fa3490 100644
--- a/video/out/vo.c
+++ b/video/out/vo.c
@@ -977,7 +977,7 @@ int vo_get_num_future_frames(struct vo *vo)
 {
     struct vo_internal *in = vo->in;
     pthread_mutex_lock(&in->lock);
-    int res = in->req_frames + 1;
+    int res = in->req_frames - 1;
     pthread_mutex_unlock(&in->lock);
     return res;
 }
diff --git a/video/out/vo.h b/video/out/vo.h
index 9e1a6db93c..f264694c08 100644
--- a/video/out/vo.h
+++ b/video/out/vo.h
@@ -177,7 +177,7 @@ struct vo_frame {
     // Warning: When OSD should be redrawn in --force-window --idle mode, this
     //          can be NULL. The VO should draw a black background, OSD on top.
     struct mp_image *current;
-    // List of future images, starting with the next one. This does not
+    // List of future images, starting with the current one. This does not
     // care about repeated frames - it simply contains the next real frames.
     // vo_set_queue_params() sets how many future frames this should include.
     // The actual number of frames delivered to the VO can be lower.