Mark, this is not a Weld limitation but a JLS requirement. I don't know the details but if you look at https://issues.jboss.org/browse/CDITCK-416?focusedCommentId=13000770&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13000770 zou can see that Weld originally returned MySuperInterface<Number> as well.