diff --git a/lib/PayPro.js b/lib/PayPro.js
index 13f79c6..d547203 100644
--- a/lib/PayPro.js
+++ b/lib/PayPro.js
@@ -298,7 +298,7 @@ PayPro.prototype.sinVerify = function() {
 // Helpers
 
 function PEMtoDER(pem) {
-  pem = pem.replace(/^-----END [^-]+-----$/gmi/, '');
+  pem = pem.replace(/^-----END [^-]+-----$/gmi, '');
   var parts = pem.split(/-----BEGIN [^-]+-----/);
   return parts.map(function(part) {
     part = part.replace(/\s+/g, '');