diff --git a/index.js b/index.js
index 6424a83..ac856a5 100644
--- a/index.js
+++ b/index.js
@@ -21,6 +21,10 @@ module.exports = function(filename, opts, cb) {
     opts.wrapper = __dirname + '/source.sh';
   }
 
+  if (!opts.shell) {
+    opts.shell = 'sh';
+  }
+
   if (!opts.reserved) {
     opts.reserved = xtend(reserved, opts.reserved);
   }
@@ -33,7 +37,7 @@ module.exports = function(filename, opts, cb) {
   var status = null;
   var stdout = null;
   var stderr = null;
-  var proc = spawn(opts.wrapper, [ filename ]);
+  var proc = spawn(opts.shell, [opts.wrapper, filename]);
   
   proc.on('error', function(err) {
     cb(err);