In most coses we call the correct constructor in Mule so this problem hasn't popped up on the radar, however, in the AstractService for 2.0.1 it is called incorrectly: http://fisheye.codehaus.org/browse/mule/branches/mule-2.x/core/src/main/java/org/mule/service/AbstractService.java?r=12151#l901 This is an easy mistake to make so I think we need to tighten up the DefaultMuleMessage constructor to not allow this to happen.