diff --git a/autoload/sy.vim b/autoload/sy.vim
index bf6bf7a..92e8352 100644
--- a/autoload/sy.vim
+++ b/autoload/sy.vim
@@ -142,3 +142,8 @@ function! sy#toggle() abort
     call sy#disable()
   endif
 endfunction
+
+" Function: #buffer_is_active {{{1
+function! sy#buffer_is_active()
+  return (!exists('b:sy') || !b:sy.active) ? 0 : 1
+endfunction