diff --git a/lib/signed-xml.js b/lib/signed-xml.js
index c579b28c..e05a3405 100644
--- a/lib/signed-xml.js
+++ b/lib/signed-xml.js
@@ -245,7 +245,9 @@ SignedXml.SignatureAlgorithms = {
 }
 
 SignedXml.defaultNsForPrefix = {
-  ds: 'http://www.w3.org/2000/09/xmldsig#'
+  ds: 'http://www.w3.org/2000/09/xmldsig#',
+  dsig: 'http://www.w3.org/2000/09/xmldsig#',
+  dsig11: 'http://www.w3.org/2009/xmldsig11#'
 };
 
 SignedXml.prototype.checkSignature = function(xml) {