--- samba-4.2.4-r1.ebuild	2015-09-21 13:44:48.082645600 -0400
+++ samba-4.2.4-r2.ebuild	2015-09-21 13:54:14.518071100 -0400
@@ -68,7 +68,8 @@
 	selinux? ( sec-policy/selinux-samba )
 "
 
-REQUIRED_USE="addc? ( gnutls )
+# AD DC and MIT-Krb5 cannot coexist (see bug #542462)
+REQUIRED_USE="addc? ( gnutls !system-mitkrb5 )
 	ads? ( acl gnutls ldap )
 	${PYTHON_REQUIRED_USE}"