diff --git a/lib/passport-wsfed-saml2/samlp.js b/lib/passport-wsfed-saml2/samlp.js
index 5b61741..17320ec 100644
--- a/lib/passport-wsfed-saml2/samlp.js
+++ b/lib/passport-wsfed-saml2/samlp.js
@@ -112,7 +112,7 @@ Samlp.prototype = {
 
     var idpUrl = options.identityProviderUrl;
     if (typeof idpUrl !== 'string' || !validUrl.isWebUri(idpUrl)) {
-      return callback(new Error(`Invalid identity provider URL: ${JSON.stringify(idpUrl)}`));
+      return callback(new Error('Invalid identity provider URL: ${JSON.stringify(idpUrl)}'));
     }
 
     var signatureAlgorithm = options.signatureAlgorithm || 'rsa-sha256';
diff --git a/package.json b/package.json
index 54f8d05..27f662c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "passport-wsfed-saml2",
-  "version": "3.0.13",
+  "version": "3.0.14",
   "description": "SAML2 Protocol and WS-Fed library",
   "scripts": {
     "test": "mocha --reporter spec --recursive"