diff --git a/sys/dev/hyperv/vmbus/vmbus.c b/sys/dev/hyperv/vmbus/vmbus.c
--- a/sys/dev/hyperv/vmbus/vmbus.c
+++ b/sys/dev/hyperv/vmbus/vmbus.c
@@ -136,8 +136,6 @@
 static int			vmbus_intr_setup(struct vmbus_softc *);
 static void			vmbus_intr_teardown(struct vmbus_softc *);
 static int			vmbus_doattach(struct vmbus_softc *);
-static void			vmbus_event_proc_dummy(struct vmbus_softc *,
-				    int);
 static struct vmbus_softc	*vmbus_sc;
 
 SYSCTL_NODE(_hw, OID_AUTO, vmbus, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
@@ -684,7 +682,8 @@
 	 * As recommended by the Windows guest fellows, we check events before
 	 * checking messages.
 	 */
-	sc->vmbus_event_proc(sc, cpu);
+	if (sc->vmbus_event_proc != NULL)
+		sc->vmbus_event_proc(sc, cpu);
 
 	/*
 	 * Check messages.  Mainly management stuffs; ultra low rate.
@@ -1483,11 +1482,6 @@
 	return (ret);
 }
 
-static void
-vmbus_event_proc_dummy(struct vmbus_softc *sc __unused, int cpu __unused)
-{
-}
-
 #if defined(EARLY_AP_STARTUP) || defined(__aarch64__)
 
 static void
@@ -1506,16 +1500,14 @@
 static int
 vmbus_attach(device_t dev)
 {
-	vmbus_sc = device_get_softc(dev);
-	vmbus_sc->vmbus_dev = dev;
-	vmbus_sc->vmbus_idtvec = -1;
-
 	/*
 	 * Event processing logic will be configured:
 	 * - After the vmbus protocol version negotiation.
 	 * - Before we request channel offers.
 	 */
-	vmbus_sc->vmbus_event_proc = vmbus_event_proc_dummy;
+	vmbus_sc = device_get_softc(dev);
+	vmbus_sc->vmbus_dev = dev;
+	vmbus_sc->vmbus_idtvec = -1;
 
 #if defined(EARLY_AP_STARTUP) || defined(__aarch64__)
 	/*