diff --git a/lib/xmlenc.js b/lib/xmlenc.js
index 4eb04fb..e02e3d0 100644
--- a/lib/xmlenc.js
+++ b/lib/xmlenc.js
@@ -136,11 +136,11 @@ function decrypt(xml, options, callback) {
 
     switch (encryptionAlgorithm) {
       case 'http://www.w3.org/2001/04/xmlenc#aes128-cbc':
-        return callback(null, decryptWithAlgorithm('aes-128-cbc', symmetricKey, 16, encrypted));
+        return decryptWithAlgorithm('aes-128-cbc', symmetricKey, 16, encrypted, callback);
       case 'http://www.w3.org/2001/04/xmlenc#aes256-cbc':
-        return callback(null, decryptWithAlgorithm('aes-256-cbc', symmetricKey, 16, encrypted));
+        return decryptWithAlgorithm('aes-256-cbc', symmetricKey, 16, encrypted, callback);
       case 'http://www.w3.org/2001/04/xmlenc#tripledes-cbc':
-        return callback(null, decryptWithAlgorithm('des-ede3-cbc', symmetricKey, 8, encrypted));
+        return decryptWithAlgorithm('des-ede3-cbc', symmetricKey, 8, encrypted, callback);
       default:
         return callback(new Error('encryption algorithm ' + encryptionAlgorithm + ' not supported'));
     }
@@ -205,7 +205,7 @@ function encryptWithAlgorithm(algorithm, symmetricKey, ivLength, content, encodi
   });
 }
 
-function decryptWithAlgorithm(algorithm, symmetricKey, ivLength, content) {
+function decryptWithAlgorithm(algorithm, symmetricKey, ivLength, content, callback) {
   var decipher = crypto.createDecipheriv(algorithm, symmetricKey, content.slice(0,ivLength));
   decipher.setAutoPadding(false);
 
@@ -216,11 +216,10 @@ function decryptWithAlgorithm(algorithm, symmetricKey, ivLength, content) {
   if (1 <= padding && padding <= ivLength) {
     decrypted = decrypted.substr(0, decrypted.length - padding);
   } else {
-    callback(new Error('padding length invalid'));
-    return;
+    return callback(new Error('padding length invalid'));
   }
 
-  return new Buffer(decrypted, 'binary').toString('utf8');
+  return callback(null, new Buffer(decrypted, 'binary').toString('utf8'));
 }
 
 exports = module.exports = {