diff --git a/src/keymapping.vim b/src/keymapping.vim
index 4605be8..940245e 100644
--- a/src/keymapping.vim
+++ b/src/keymapping.vim
@@ -10,7 +10,7 @@ map <silent><F3> :nohl<CR>
 "" Toggle number
 map <silent><F4> :set number!<CR>
 "" AG search
-nmap ' :Ag<space>
+nmap ' :Ack<Space>
 "" Browse
 map <silent> - :NERDTreeToggle<CR>
 "" Selection
diff --git a/src/plugins.vim b/src/plugins.vim
index c8fd131..35b7217 100644
--- a/src/plugins.vim
+++ b/src/plugins.vim
@@ -72,8 +72,11 @@ let g:ctrlp_cmd='CtrlPMixed'
 let g:ctrlp_working_path_mode='ra'
 
 " ag: searching
-Plug 'rking/ag.vim'
+Plug 'mileszs/ack.vim'
 let g:ag_working_path_mode ="r"
+if executable('ag')
+    let g:ackprg = 'ag --vimgrep --smart-case'
+endif
 
 " vim-gitgutter: add git status in gutter
 Plug 'airblade/vim-gitgutter'