diff --git a/autoload/ack.vim b/autoload/ack.vim
index 82d3de65..a58995e4 100644
--- a/autoload/ack.vim
+++ b/autoload/ack.vim
@@ -11,7 +11,7 @@ endif
 " Public API
 "-----------------------------------------------------------------------------
 
-function! ack#Ack(cmd, args) "{{{
+function! ack#Ack(cmd, args, paths) "{{{
   call s:Init(a:cmd)
   redraw
 
@@ -37,6 +37,11 @@ function! ack#Ack(cmd, args) "{{{
   " If no pattern is provided, search for the word under the cursor
   let l:grepargs = empty(a:args) ? expand("<cword>") : a:args . join(a:000, ' ')
 
+  " Add paths to search in
+  if len(a:paths) > 0
+    let l:grepargs .= ' '.join(a:paths, ' ')
+  endif
+
   "Bypass search if cursor is on blank string
   if l:grepargs == ""
     echo "No regular expression found."
@@ -65,12 +70,11 @@ function! ack#AckFromSearch(cmd, args) "{{{
   let search = getreg('/')
   " translate vim regular expression to perl regular expression.
   let search = substitute(search, '\(\\<\|\\>\)', '\\b', 'g')
-  call ack#Ack(a:cmd, '"' . search . '" ' . a:args)
+  call ack#Ack(a:cmd, '"' . search . '" ' . a:args, [])
 endfunction "}}}
 
 function! ack#AckHelp(cmd, args) "{{{
-  let args = a:args . ' ' . s:GetDocLocations()
-  call ack#Ack(a:cmd, args)
+  call ack#Ack(a:cmd, a:args, s:GetDocPaths())
 endfunction "}}}
 
 function! ack#AckWindow(cmd, args) "{{{
@@ -85,9 +89,8 @@ function! ack#AckWindow(cmd, args) "{{{
 
   " expand to full path (avoid problems with cd/lcd in au QuickFixCmdPre)
   let files = map(files, "shellescape(fnamemodify(v:val, ':p'))")
-  let args = a:args . ' ' . join(files)
 
-  call ack#Ack(a:cmd, args)
+  call ack#Ack(a:cmd, a:args, files)
 endfunction "}}}
 
 function! ack#ShowResults() "{{{
@@ -133,12 +136,12 @@ function! s:ApplyMappings() "{{{
   endif
 endfunction "}}}
 
-function! s:GetDocLocations() "{{{
-  let dp = ''
+function! s:GetDocPaths() "{{{
+  let dp = []
   for p in split(&rtp, ',')
     let p = p . '/doc/'
     if isdirectory(p)
-      let dp = p . '*.txt ' . dp
+      call insert(dp, p . '*.txt')
     endif
   endfor
 
diff --git a/plugin/ack.vim b/plugin/ack.vim
index 2be8197d..06df2103 100644
--- a/plugin/ack.vim
+++ b/plugin/ack.vim
@@ -67,12 +67,12 @@ if !exists("g:ack_use_cword_for_empty_search")
   let g:ack_use_cword_for_empty_search = 1
 endif
 
-command! -bang -nargs=* -complete=file Ack           call ack#Ack('grep<bang>', <q-args>)
-command! -bang -nargs=* -complete=file AckAdd        call ack#Ack('grepadd<bang>', <q-args>)
+command! -bang -nargs=* -complete=file Ack           call ack#Ack('grep<bang>', <q-args>, [])
+command! -bang -nargs=* -complete=file AckAdd        call ack#Ack('grepadd<bang>', <q-args>, [])
 command! -bang -nargs=* -complete=file AckFromSearch call ack#AckFromSearch('grep<bang>', <q-args>)
-command! -bang -nargs=* -complete=file LAck          call ack#Ack('lgrep<bang>', <q-args>)
-command! -bang -nargs=* -complete=file LAckAdd       call ack#Ack('lgrepadd<bang>', <q-args>)
-command! -bang -nargs=* -complete=file AckFile       call ack#Ack('grep<bang> -g', <q-args>)
+command! -bang -nargs=* -complete=file LAck          call ack#Ack('lgrep<bang>', <q-args>, [])
+command! -bang -nargs=* -complete=file LAckAdd       call ack#Ack('lgrepadd<bang>', <q-args>, [])
+command! -bang -nargs=* -complete=file AckFile       call ack#Ack('grep<bang> -g', <q-args>, [])
 command! -bang -nargs=* -complete=help AckHelp       call ack#AckHelp('grep<bang>', <q-args>)
 command! -bang -nargs=* -complete=help LAckHelp      call ack#AckHelp('lgrep<bang>', <q-args>)
 command! -bang -nargs=*                AckWindow     call ack#AckWindow('grep<bang>', <q-args>)