diff --git a/autoload/nerdtree/ui_glue.vim b/autoload/nerdtree/ui_glue.vim
index 5e08a0d..3bd74ce 100644
--- a/autoload/nerdtree/ui_glue.vim
+++ b/autoload/nerdtree/ui_glue.vim
@@ -208,8 +208,8 @@ endfunction
 " FUNCTION: s:closeTreeWindow() {{{1
 " close the tree window
 function! s:closeTreeWindow()
-    if b:NERDTree.isWinTree() && b:NERDTreePreviousBuf != -1
-        exec "buffer " . b:NERDTreePreviousBuf
+    if b:NERDTree.isWinTree() && b:NERDTree.previousBuf() != -1
+        exec "buffer " . b:NERDTree.previousBuf()
     else
         if winnr("$") > 1
             call g:NERDTree.Close()
diff --git a/lib/nerdtree/creator.vim b/lib/nerdtree/creator.vim
index 87407d7..7289d3f 100644
--- a/lib/nerdtree/creator.vim
+++ b/lib/nerdtree/creator.vim
@@ -103,8 +103,8 @@ function! s:Creator.createWindowTree(dir)
     "all independent
     exec "silent edit " . self._nextBufferName()
 
-    let b:NERDTreePreviousBuf = bufnr(previousBuf)
     call self._createNERDTree(path, "window")
+    let b:NERDTree._previousBuf = bufnr(previousBuf)
     call self._setCommonBufOptions()
 
     call b:NERDTree.render()
diff --git a/lib/nerdtree/nerdtree.vim b/lib/nerdtree/nerdtree.vim
index 801282e..db55cb9 100644
--- a/lib/nerdtree/nerdtree.vim
+++ b/lib/nerdtree/nerdtree.vim
@@ -140,6 +140,10 @@ function! s:NERDTree.PathFilters()
     return s:NERDTree._PathFilters
 endfunction
 
+"FUNCTION: s:NERDTree.previousBuf() {{{1
+function! s:NERDTree.previousBuf()
+    return self._previousBuf
+endfunction
 
 "FUNCTION: s:NERDTree.render() {{{1
 "A convenience function - since this is called often