diff --git a/lib/nerdtree/ui.vim b/lib/nerdtree/ui.vim
index ff85589..6ff9878 100644
--- a/lib/nerdtree/ui.vim
+++ b/lib/nerdtree/ui.vim
@@ -282,7 +282,7 @@ endfunction
 function! s:UI._indentLevelFor(line)
     " Replace multi-character DirArrows with a single space so the
     " indentation calculation doesn't get messed up.
-    let l:line = substitute(substitute(a:line, g:NERDTreeDirArrowExpandable, ' ', ''), g:NERDTreeDirArrowCollapsible, ' ', '')
+    let l:line = substitute(substitute(a:line, '\V'.g:NERDTreeDirArrowExpandable, ' ', ''), '\V'.g:NERDTreeDirArrowCollapsible, ' ', '')
     let leadChars = match(l:line, '\M\[^ ]')
     return leadChars / s:UI.IndentWid()
 endfunction