diff --git a/mutalyzer/services/soap.py b/mutalyzer/services/soap.py
index 278841d00b83350058cfdfa99bb854cc42a01b46..715a2456c12734c4941ebe17104656fc5425b763 100644
--- a/mutalyzer/services/soap.py
+++ b/mutalyzer/services/soap.py
@@ -13,7 +13,8 @@ from mutalyzer.services import rpc
 
 # SOAP/1.1 application.
 application = Application([rpc.MutalyzerService], tns=mutalyzer.SOAP_NAMESPACE,
-                          in_protocol=Soap11(), out_protocol=Soap11(),
+                          in_protocol=Soap11(validator='lxml'),
+                          out_protocol=Soap11(),
                           name='Mutalyzer')