diff --git a/sys/net/debugnet.h b/sys/net/debugnet.h
--- a/sys/net/debugnet.h
+++ b/sys/net/debugnet.h
@@ -262,8 +262,9 @@
 
 #define	DEBUGNET_NOTIFY_MTU(ifp)	debugnet_any_ifnet_update(ifp)
 
+void if_setdebugnet_methods(struct ifnet *, struct debugnet_methods *);
 #define	DEBUGNET_SET(ifp, driver)				\
-	(ifp)->if_debugnet_methods = &driver##_debugnet_methods
+	if_setdebugnet_methods((ifp), &driver##_debugnet_methods)
 
 #else /* !DEBUGNET || !INET */
 
diff --git a/sys/net/if.c b/sys/net/if.c
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -4815,6 +4815,12 @@
 	ifp->if_get_counter = fn;
 }
 
+void
+if_setdebugnet_methods(if_t ifp, struct debugnet_methods *m)
+{
+	ifp->if_debugnet_methods = m;
+}
+
 #ifdef DDB
 static void
 if_show_ifnet(struct ifnet *ifp)