diff --git a/.vimrc b/.vimrc
index 2a5c4ee..2669bfd 100644
--- a/.vimrc
+++ b/.vimrc
@@ -301,9 +301,32 @@ function! s:ExecuteInShell(command)
   echo 'Execution of ' . command . ' complete.'
 endfunction
 
-
 command! -complete=shellcmd -nargs=+ Shell call s:ExecuteInShellOutput(<q-args>)
 command! -complete=shellcmd -nargs=+ Exec call s:ExecuteInShell(<q-args>)
 command! -nargs=* Make call s:ExecuteInShellOutput('make '.<q-args>)
 command! -nargs=* Git call s:ExecuteInShellOutput('git '.<q-args>)
 command! -nargs=* PTW call s:ExecuteInShell('ptw post --client=vim "'.<q-args>.'"')
+
+" Highlight all instances of word under cursor, when idle.
+" Useful when studying strange source code.
+" Type z/ to toggle highlighting on/off.
+nnoremap z/ :if AutoHighlightToggle()<Bar>set hls<Bar>else<Bar>set nohls<Bar>endif<CR>
+function! AutoHighlightToggle()
+  let @/ = ''
+  if exists('#auto_highlight')
+    au! auto_highlight
+    augroup! auto_highlight
+    setl updatetime=4000
+    echo 'Highlight current word: off'
+    return 0
+  else
+    augroup auto_highlight
+      au!
+      au CursorHold * let @/ = '\V\<'.escape(expand('<cword>'), '\').'\>'
+    augroup end
+    setl updatetime=500
+    echo 'Highlight current word: ON'
+    return 1
+  endif
+endfunction
+