diff --git a/index.js b/index.js
index 8f2e570..3d9eccf 100644
--- a/index.js
+++ b/index.js
@@ -213,7 +213,8 @@ function init (options) {
 }
 
 function getMainModule () {
-  return require.main._simulateRepl ? undefined : require.main
+  var main = require.main
+  return main && main._simulateRepl ? undefined : main
 }
 
 module.exports = init