diff --git a/hw/display/cg3.c b/hw/display/cg3.c
index 4fb67c6b1c..a1ede10394 100644
--- a/hw/display/cg3.c
+++ b/hw/display/cg3.c
@@ -287,9 +287,8 @@ static void cg3_initfn(Object *obj)
     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
     CG3State *s = CG3(obj);
 
-    memory_region_init_ram_nomigrate(&s->rom, obj, "cg3.prom", FCODE_MAX_ROM_SIZE,
-                           &error_fatal);
-    memory_region_set_readonly(&s->rom, true);
+    memory_region_init_rom_nomigrate(&s->rom, obj, "cg3.prom",
+                                     FCODE_MAX_ROM_SIZE, &error_fatal);
     sysbus_init_mmio(sbd, &s->rom);
 
     memory_region_init_io(&s->reg, obj, &cg3_reg_ops, s, "cg3.reg",
diff --git a/hw/display/tcx.c b/hw/display/tcx.c
index ca458f94fe..76de16e8ea 100644
--- a/hw/display/tcx.c
+++ b/hw/display/tcx.c
@@ -755,9 +755,8 @@ static void tcx_initfn(Object *obj)
     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
     TCXState *s = TCX(obj);
 
-    memory_region_init_ram_nomigrate(&s->rom, obj, "tcx.prom", FCODE_MAX_ROM_SIZE,
-                           &error_fatal);
-    memory_region_set_readonly(&s->rom, true);
+    memory_region_init_rom_nomigrate(&s->rom, obj, "tcx.prom",
+                                     FCODE_MAX_ROM_SIZE, &error_fatal);
     sysbus_init_mmio(sbd, &s->rom);
 
     /* 2/STIP : Stippler */