diff --git a/autoload/fzf/vim.vim b/autoload/fzf/vim.vim
index 6b58161..d522e33 100644
--- a/autoload/fzf/vim.vim
+++ b/autoload/fzf/vim.vim
@@ -31,7 +31,7 @@ set cpo&vim
 let s:layout_keys = ['window', 'up', 'down', 'left', 'right']
 let s:bin_dir = expand('<sfile>:h:h:h').'/bin/'
 let s:bin = {
-\ 'preview': s:bin_dir.executable('ruby') ? 'preview.rb' : 'preview.sh',
+\ 'preview': s:bin_dir.(executable('ruby') ? 'preview.rb' : 'preview.sh'),
 \ 'tags':    s:bin_dir.'tags.pl' }
 let s:TYPE = {'dict': type({}), 'funcref': type(function('call')), 'string': type('')}