diff --git a/autoload/nerdtree/ui_glue.vim b/autoload/nerdtree/ui_glue.vim
index 0cc3362..6ba9ee6 100644
--- a/autoload/nerdtree/ui_glue.vim
+++ b/autoload/nerdtree/ui_glue.vim
@@ -29,9 +29,9 @@ function! nerdtree#ui_glue#createDefaultBindings()
 
     call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapOpenRecursively, 'scope': "DirNode", 'callback': s."openNodeRecursively" })
 
-    call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapUpdir, 'scope': "all", 'callback': s."upDirCurrentRootClosed" })
-    call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapUpdirKeepOpen, 'scope': "all", 'callback': s."upDirCurrentRootOpen" })
-    call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapChangeRoot, 'scope': "Node", 'callback': s."chRoot" })
+    call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapUpdir, 'scope': 'all', 'callback': s . 'upDirCurrentRootClosed' })
+    call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapUpdirKeepOpen, 'scope': 'all', 'callback': s . 'upDirCurrentRootOpen' })
+    call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapChangeRoot, 'scope': 'Node', 'callback': s . 'chRoot' })
 
     call NERDTreeAddKeyMap({ 'key': g:NERDTreeMapChdir, 'scope': "Node", 'callback': s."chCwd" })
 
@@ -619,40 +619,33 @@ function! s:toggleZoom()
     call b:NERDTree.ui.toggleZoom()
 endfunction
 
-"FUNCTION: nerdtree#ui_glue#upDir(keepState) {{{1
-"moves the tree up a level
+" FUNCTION: nerdtree#ui_glue#upDir(preserveState) {{{1
+" Move the NERDTree up one level.
 "
-"Args:
-"keepState: 1 if the current root should be left open when the tree is
-"re-rendered
-function! nerdtree#ui_glue#upDir(keepState)
-    let cwd = b:NERDTree.root.path.str({'format': 'UI'})
-    if cwd ==# "/" || cwd =~# '^[^/]..$'
-        call nerdtree#echo("already at top dir")
-    else
-        if !a:keepState
-            call b:NERDTree.root.close()
-        endif
+" Args:
+" preserveState: if 1, the current root is left open when the new tree is
+" rendered; if 0, the current root node is closed
+function! nerdtree#ui_glue#upDir(preserveState)
 
-        let oldRoot = b:NERDTree.root
+    try
+        call b:NERDTree.root.cacheParent()
+    catch /^NERDTree.CannotCacheParentError/
+        call nerdtree#echo('already at root directory')
+        return
+    endtry
 
-        if empty(b:NERDTree.root.parent)
-            let path = b:NERDTree.root.path.getParent()
-            let newRoot = g:NERDTreeDirNode.New(path, b:NERDTree)
-            call newRoot.open()
-            call newRoot.transplantChild(b:NERDTree.root)
-            let b:NERDTree.root = newRoot
-        else
-            let b:NERDTree.root = b:NERDTree.root.parent
-        endif
+    let l:oldRoot = b:NERDTree.root
+    let l:newRoot = b:NERDTree.root.parent
 
-        if g:NERDTreeChDirMode ==# 2
-            call b:NERDTree.root.path.changeToDir()
-        endif
+    call l:newRoot.open()
+    call l:newRoot.transplantChild(l:oldRoot)
 
-        call b:NERDTree.render()
-        call oldRoot.putCursorHere(0, 0)
+    if !a:preserveState
+        call l:oldRoot.close()
     endif
+
+    call b:NERDTree.changeRoot(l:newRoot)
+    call l:oldRoot.putCursorHere(0, 0)
 endfunction
 
 " FUNCTION: s:upDirCurrentRootOpen() {{{1