gistfile1.diff

diff --git a/autoload/twitvim.vim b/autoload/twitvim.vim
index e5b3677..e9af6e1 100644
--- a/autoload/twitvim.vim
+++ b/autoload/twitvim.vim
@@ -57,6 +57,29 @@ function! s:get_api_root()
     return svc == '' ? s:default_api_root : s:service_info[svc]['api_root']
 endfunction
 
+try
+  call vimproc#version()
+  let s:has_vimproc = 1
+catch
+  let s:has_vimproc = 0
+endtry
+
+function! s:shell_error()
+    if s:has_vimproc
+       return vimproc#get_last_status()
+    else
+       return v:shell_error
+    endif
+endfunction
+
+function! s:system(...)
+    if s:has_vimproc
+       return call('vimproc#system', a:000)
+    else
+       return call('system', a:000)
+    endif
+endfunction
+
 " Service display name.
 function! s:get_svc_disp_name()
     return s:service_info[s:cur_service]['dispname']
@@ -806,8 +829,8 @@ endfunction
 
 " Compute HMAC-SHA1 digest by running openssl command line utility.
 function! s:openssl_hmac_sha1_digest(key, str)
-    let output = system('openssl dgst -binary -sha1 -hmac "'.a:key.'" | openssl base64', a:str)
-    if v:shell_error != 0
+    let output = s:system('openssl dgst -binary -sha1 -hmac "'.a:key.'" | openssl base64', a:str)
+    if s:shell_error() != 0
         call s:errormsg("Error running openssl command: ".output)
         return ""
     endif
@@ -1203,14 +1226,14 @@ function! s:curl_curl(url, login, proxy, proxylogin, parms)
     if got_json
         let curlcmd .= '-H "Content-Type: application/json" '
     endif
-    
+
     let curlcmd .= '-H "User-Agent: '.s:user_agent.'" '
 
     let curlcmd .= '"'.a:url.'"'
 
-    let output = system(curlcmd)
+    let output = s:system(curlcmd)
     let errormsg = s:xml_get_element(output, 'error')
-    if v:shell_error != 0
+    if s:shell_error() != 0
         let error = output
     elseif errormsg != ''
         let error = errormsg