diff --git a/src/saml2/saml.py b/src/saml2/saml.py
index a764782..c7c05f8 100644
--- a/src/saml2/saml.py
+++ b/src/saml2/saml.py
@@ -441,7 +441,7 @@ class SubjectConfirmationDataType_(SamlBase):
     c_attributes = SamlBase.c_attributes.copy()
     c_child_order = SamlBase.c_child_order[:]
     c_cardinality = SamlBase.c_cardinality.copy()
-    c_attributes['NotBefore'] = ('not_before', 'AsTime', False)
+    c_attributes['NotBefore'] = ('not_before', 'dateTime', False)
     c_attributes['NotOnOrAfter'] = ('not_on_or_after', 'dateTime', False)
     c_attributes['Recipient'] = ('recipient', 'anyURI', False)
     c_attributes['InResponseTo'] = ('in_response_to', 'NCName', False)
diff --git a/tests/test_02_saml.py b/tests/test_02_saml.py
index 16921a5..ffce4a3 100644
--- a/tests/test_02_saml.py
+++ b/tests/test_02_saml.py
@@ -851,6 +851,13 @@ class TestSubjectConfirmation:
         assert sc.subject_confirmation_data.in_response_to == "responseID"
         assert sc.subject_confirmation_data.address == "127.0.0.1"
 
+    def testVerify(self):
+        """Test SubjectConfirmation verify"""
+
+        sc = saml.subject_confirmation_from_string(
+            saml2_data.TEST_SUBJECT_CONFIRMATION)
+        assert sc.verify()
+
 
 class TestSubject:
     def setup_class(self):