diff --git a/plugin/NERD_tree.vim b/plugin/NERD_tree.vim
index 978d53d..b669e8d 100644
--- a/plugin/NERD_tree.vim
+++ b/plugin/NERD_tree.vim
@@ -3533,7 +3533,7 @@ endfunction
 
 "FUNCTION: s:previewNode() {{{2
 function! s:previewNode(openNewWin)
-    let currentBuf = bufnr(".")
+    let currentBuf = bufnr("")
     if a:openNewWin
         call s:openEntrySplit(1)
     else