diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
index e759eb5f83..a89cf4c129 100644
--- a/hw/s390x/s390-virtio-ccw.c
+++ b/hw/s390x/s390-virtio-ccw.c
@@ -154,14 +154,12 @@ static void virtio_ccw_register_hcalls(void)
                                    virtio_ccw_hcall_early_printk);
 }
 
-static void s390_memory_init(ram_addr_t mem_size)
+static void s390_memory_init(MemoryRegion *ram)
 {
     MemoryRegion *sysmem = get_system_memory();
-    MemoryRegion *ram = g_new(MemoryRegion, 1);
     Error *local_err = NULL;
 
     /* allocate RAM for core */
-    memory_region_allocate_system_memory(ram, NULL, "s390.ram", mem_size);
     memory_region_add_subregion(sysmem, 0, ram);
 
     /*
@@ -245,7 +243,7 @@ static void ccw_init(MachineState *machine)
 
     s390_sclp_init();
     /* init memory + setup max page size. Required for the CPU model */
-    s390_memory_init(machine->ram_size);
+    s390_memory_init(machine->ram);
 
     /* init CPUs (incl. CPU model) early so s390_has_feature() works */
     s390_init_cpus(machine);
@@ -471,6 +469,7 @@ static void ccw_machine_class_init(ObjectClass *oc, void *data)
     hc->plug = s390_machine_device_plug;
     hc->unplug_request = s390_machine_device_unplug_request;
     nc->nmi_monitor_handler = s390_nmi;
+    mc->default_ram_id = "s390.ram";
 }
 
 static inline bool machine_get_aes_key_wrap(Object *obj, Error **errp)