diff --git a/hw/arm/mps2-tz.c b/hw/arm/mps2-tz.c
index f8b620bcc6..a8dea7dde1 100644
--- a/hw/arm/mps2-tz.c
+++ b/hw/arm/mps2-tz.c
@@ -39,6 +39,7 @@
 
 #include "qemu/osdep.h"
 #include "qemu/units.h"
+#include "qemu/cutils.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "hw/arm/boot.h"
@@ -79,7 +80,6 @@ typedef struct {
     MachineState parent;
 
     ARMSSE iotkit;
-    MemoryRegion psram;
     MemoryRegion ssram[3];
     MemoryRegion ssram1_m;
     MPS2SCC scc;
@@ -388,6 +388,13 @@ static void mps2tz_common_init(MachineState *machine)
         exit(1);
     }
 
+    if (machine->ram_size != mc->default_ram_size) {
+        char *sz = size_to_str(mc->default_ram_size);
+        error_report("Invalid RAM size, should be %s", sz);
+        g_free(sz);
+        exit(EXIT_FAILURE);
+    }
+
     sysbus_init_child_obj(OBJECT(machine), "iotkit", &mms->iotkit,
                           sizeof(mms->iotkit), mmc->armsse_type);
     iotkitdev = DEVICE(&mms->iotkit);
@@ -458,9 +465,7 @@ static void mps2tz_common_init(MachineState *machine)
      * tradeoffs. For QEMU they're all just RAM, though. We arbitrarily
      * call the 16MB our "system memory", as it's the largest lump.
      */
-    memory_region_allocate_system_memory(&mms->psram,
-                                         NULL, "mps.ram", 16 * MiB);
-    memory_region_add_subregion(system_memory, 0x80000000, &mms->psram);
+    memory_region_add_subregion(system_memory, 0x80000000, machine->ram);
 
     /* The overflow IRQs for all UARTs are ORed together.
      * Tx, Rx and "combined" IRQs are sent to the NVIC separately.
@@ -642,6 +647,8 @@ static void mps2tz_class_init(ObjectClass *oc, void *data)
 
     mc->init = mps2tz_common_init;
     iic->check = mps2_tz_idau_check;
+    mc->default_ram_size = 16 * MiB;
+    mc->default_ram_id = "mps.ram";
 }
 
 static void mps2tz_an505_class_init(ObjectClass *oc, void *data)