diff --git a/src/onelogin/saml2/response.py b/src/onelogin/saml2/response.py
index d69242d3..d1b74620 100644
--- a/src/onelogin/saml2/response.py
+++ b/src/onelogin/saml2/response.py
@@ -792,8 +792,10 @@ def __query_assertion(self, xpath_expr):
             # Check if the message is signed
             signed_message_query = '/samlp:Response' + signature_expr
             message_reference_nodes = self.__query(signed_message_query)
-            if message_reference_nodes:
-                message_id = message_reference_nodes[0].get('URI')
+            # we can have reference node but URI can be empty
+            message_id = message_reference_nodes and \
+                message_reference_nodes[0].get('URI')
+            if message_id:
                 final_query = "/samlp:Response[@ID=$tagid]/"
                 tagid = message_id[1:]
             else:
@@ -801,8 +803,11 @@ def __query_assertion(self, xpath_expr):
             final_query += assertion_expr
         else:
             assertion_id = assertion_reference_nodes[0].get('URI')
-            final_query = '/samlp:Response' + assertion_expr + "[@ID=$tagid]"
-            tagid = assertion_id[1:]
+            if assertion_id:
+                final_query = '/samlp:Response' + assertion_expr + "[@ID=$tagid]"
+                tagid = assertion_id[1:]
+            else:
+                final_query = '/samlp:Response' + assertion_expr
         final_query += xpath_expr
         return self.__query(final_query, tagid)
 
diff --git a/tests/data/responses/response_with_empty_assertion_reference_uri.xml.base64 b/tests/data/responses/response_with_empty_assertion_reference_uri.xml.base64
new file mode 100644
index 00000000..1b5171bf
--- /dev/null
+++ b/tests/data/responses/response_with_empty_assertion_reference_uri.xml.base64
@@ -0,0 +1,69 @@
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diff --git a/tests/data/responses/valid_response_with_unsigned_assertion.xml.base64 b/tests/data/responses/valid_response_with_unsigned_assertion.xml.base64
new file mode 100644
index 00000000..720c5fe4
--- /dev/null
+++ b/tests/data/responses/valid_response_with_unsigned_assertion.xml.base64
@@ -0,0 +1 @@
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
diff --git a/tests/src/OneLogin/saml2_tests/response_test.py b/tests/src/OneLogin/saml2_tests/response_test.py
index a51f8e60..63084e86 100644
--- a/tests/src/OneLogin/saml2_tests/response_test.py
+++ b/tests/src/OneLogin/saml2_tests/response_test.py
@@ -633,6 +633,22 @@ def testQueryAssertions(self):
         response_7 = OneLogin_Saml2_Response(settings, xml_7)
         self.assertEqual(['http://idp.example.com/'], response_7.get_issuers())
 
+    def testQueryAssertionsWithEmptyRefenceURI(self):
+        """
+        Tests the __query_assertion if //Signature/Reference/@URI is empty.
+        """
+        settings = OneLogin_Saml2_Settings(self.loadSettingsJSON())
+
+        # test signed message without reference URI
+        xml = self.file_contents(join(self.data_path, 'responses', 'response_without_reference_uri.xml.base64'))
+        response = OneLogin_Saml2_Response(settings, xml)
+        self.assertEqual('saml@user.com', response.get_nameid())
+
+        # test signed assertion without reference URI
+        xml = self.file_contents(join(self.data_path, 'responses', 'response_with_empty_assertion_reference_uri.xml.base64'))
+        response = OneLogin_Saml2_Response(settings, xml)
+        self.assertEqual('support@onelogin.com', response.get_nameid())
+
     def testGetIssuers(self):
         """
         Tests the get_issuers method of the OneLogin_Saml2_Response