diff --git a/shell.js b/shell.js
index 9ab370f..e69d197 100644
--- a/shell.js
+++ b/shell.js
@@ -81,6 +81,8 @@ function system(tag, cmd, options, callback) {
     cp.stderr.on('data', function (data) {
         debug(tag + ' (stderr): %s', data.toString('utf8'));
     });
+
+    return cp;
 }
 
 function sudo(tag, args, callback) {