diff --git a/lib/browser/PayPro.js b/lib/browser/PayPro.js
index 10a7697..52e98fb 100644
--- a/lib/browser/PayPro.js
+++ b/lib/browser/PayPro.js
@@ -20,12 +20,12 @@ PayPro.sign = function(key) {
     var pki_data = this.get('pki_data'); // contains one or more x509 certs
     var type = pki_type.split('+').toUpperCase();
     var buf = this.serializeForSig();
-    var jsrsaSig = KJUR.crypto.Signature({
+    var jsrsaSig = new KJUR.crypto.Signature({
       alg: type + 'withRSA',
       prov: 'cryptojs/jsrsa'
     });
     jsrsaSig.initSign(pki_data);
-    jsrsaSig.updateString(buf.toString());
+    jsrsaSig.updateHex(buf.toString('hex'));
     var sig = new Buffer(jsrsasig.sign(), 'hex');
   } else if (pki_type === 'none') {
     return this;
@@ -33,7 +33,6 @@ PayPro.sign = function(key) {
     throw new Error('Unsupported pki_type');
   }
 
-
   this.set('signature', sig);
   return this;
 };
@@ -52,16 +51,16 @@ PayPro.verify = function() {
     var buf = this.serializeForSig();
     var type = pki_type.split('+').toUpperCase();
 
-    var jsrsaSig = KJUR.crypto.Signature({
+    var jsrsaSig = new KJUR.crypto.Signature({
       alg: type + 'withRSA',
       prov: 'cryptojs/jsrsa'
     });
 
     jsrsaSig.initVerifyByCertificatePEM(pki_data);
 
-    jsrsaSig.updateString(buf.toString());
+    jsrsaSig.updateHex(buf.toString('hex'));
 
-    var result = jsrsaSig.verify(sig.toString(16)); // should be hex
+    var result = jsrsaSig.verify(sig.toString('hex'));
 
     return result;
   } else if (pki_type === 'none') {