diff --git a/lib/index.js b/lib/index.js
index 5485fcd..e3936ea 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -115,8 +115,8 @@ function noQsMethod (options) {
 function authorize (options, onConnection) {
   options = xtend({ decodedPropertyName: 'decoded_token', encodedPropertyName: 'encoded_token' }, options);
 
-  if (typeof options.secret !== 'string') {
-    throw new Error(`Provided secret "${options.secret}" is invalid, must be of type string.`)
+  if (typeof options.secret !== 'string' && typeof options.secret !== 'function') {
+    throw new Error('Provided secret "' + options.secret + '" is invalid, must be of type string or function.');
   }
 
   if (!options.handshake) {