diff --git a/src/saml2/saml.py b/src/saml2/saml.py
index 0100033..90434b2 100644
--- a/src/saml2/saml.py
+++ b/src/saml2/saml.py
@@ -855,7 +855,7 @@ def _decode_attribute_value(typ, text):
         return str(float(text))
     if typ == XSD + "boolean":
         return "%s" % (text == "true")
-    if typ == NS_SOAP_ENC + "base64":
+    if typ == XSD + "base64Binary":
         import base64
         return base64.decodestring(text)
     raise ValueError("type %s not supported" % type)
diff --git a/src/saml2/utils.py b/src/saml2/utils.py
index 324c514..755a4c7 100644
--- a/src/saml2/utils.py
+++ b/src/saml2/utils.py
@@ -168,7 +168,7 @@ def make_instance(klass, spec, base64encode=False):
             if base64encode:
                 import base64
                 val = base64.encodestring(val)
-                setattr(klass_inst, "type", saml.NS_SOAP_ENC + "base64")
+                setattr(klass_inst, "type", "xs:base64Binary")
             else:
                 if isinstance(val, basestring):
                     print "basestring"
diff --git a/tests/test_01_saml.py b/tests/test_01_saml.py
index c21893b..8b1cffa 100644
--- a/tests/test_01_saml.py
+++ b/tests/test_01_saml.py
@@ -400,7 +400,7 @@ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic"
 Name="FirstName">
 <AttributeValue 
-xsi:type="http://schemas.xmlsoap.org/soap/encoding/base64">VU5JTkVUVA==</AttributeValue>
+xsi:type="xs:base64Binary">VU5JTkVUVA==</AttributeValue>
 </Attribute>"""
 
 X500_AV = """<?xml version="1.0" encoding="utf-8"?>
diff --git a/tests/test_11_utils.py b/tests/test_11_utils.py
index c2e7dc2..bfd5565 100644
--- a/tests/test_11_utils.py
+++ b/tests/test_11_utils.py
@@ -152,7 +152,7 @@ def test_attribute_base64():
     assert inst.name == "name"
     assert len(inst.attribute_value) == 1
     av = inst.attribute_value[0]
-    assert av.type == "http://schemas.xmlsoap.org/soap/encoding/base64"
+    assert av.type == "xs:base64Binary"
     assert av.text.strip() == "U2VsbWEgTGFnZXJsw7Zm"
     
 def test_attribute_statement():