diff --git a/autoload/smoothie.vim b/autoload/smoothie.vim
index b61904f..73e0b0d 100644
--- a/autoload/smoothie.vim
+++ b/autoload/smoothie.vim
@@ -183,7 +183,7 @@ endfunction
 " TODO: current algorithm is rather crude, would be good to research better
 " alternatives.
 function s:compute_velocity()
-  return g:smoothie_base_speed * (s:target_displacement + s:subline_position)
+  return g:smoothie_base_speed * (s:target_displacement - s:subline_position)
 endfunction
 
 ""