diff --git a/hw/core/bus.c b/hw/core/bus.c
index e6baa04e52..17bc1edcde 100644
--- a/hw/core/bus.c
+++ b/hw/core/bus.c
@@ -97,10 +97,9 @@ static void qbus_realize(BusState *bus, DeviceState *parent, const char *name)
         bus->parent->num_child_bus++;
         object_property_add_child(OBJECT(bus->parent), bus->name, OBJECT(bus), NULL);
         object_unref(OBJECT(bus));
-    } else if (bus != sysbus_get_default()) {
-        /* TODO: once all bus devices are qdevified,
-           only reset handler for main_system_bus should be registered here. */
-        qemu_register_reset(qbus_reset_all_fn, bus);
+    } else {
+        /* The only bus without a parent is the main system bus */
+        assert(bus == sysbus_get_default());
     }
 }
 
@@ -109,18 +108,16 @@ static void bus_unparent(Object *obj)
     BusState *bus = BUS(obj);
     BusChild *kid;
 
+    /* Only the main system bus has no parent, and that bus is never freed */
+    assert(bus->parent);
+
     while ((kid = QTAILQ_FIRST(&bus->children)) != NULL) {
         DeviceState *dev = kid->child;
         object_unparent(OBJECT(dev));
     }
-    if (bus->parent) {
-        QLIST_REMOVE(bus, sibling);
-        bus->parent->num_child_bus--;
-        bus->parent = NULL;
-    } else {
-        assert(bus != sysbus_get_default()); /* main_system_bus is never freed */
-        qemu_unregister_reset(qbus_reset_all_fn, bus);
-    }
+    QLIST_REMOVE(bus, sibling);
+    bus->parent->num_child_bus--;
+    bus->parent = NULL;
 }
 
 void qbus_create_inplace(void *bus, size_t size, const char *typename,