diff --git a/autoload/airline/extensions/commandt.vim b/autoload/airline/extensions/commandt.vim
index 2c55675f..ac74affc 100644
--- a/autoload/airline/extensions/commandt.vim
+++ b/autoload/airline/extensions/commandt.vim
@@ -8,5 +8,5 @@ function! airline#extensions#commandt#apply()
 endfunction
 
 function! airline#extensions#commandt#init(ext)
-  call ext.add_statusline_funcref(function('airline#extensions#commandt#apply'))
+  call a:ext.add_statusline_funcref(function('airline#extensions#commandt#apply'))
 endfunction