diff --git a/hw/core/platform-bus.c b/hw/core/platform-bus.c
index 22c5f76dd0..d494e5cec1 100644
--- a/hw/core/platform-bus.c
+++ b/hw/core/platform-bus.c
@@ -187,7 +187,8 @@ static void platform_bus_realize(DeviceState *dev, Error **errp)
     d = SYS_BUS_DEVICE(dev);
     pbus = PLATFORM_BUS_DEVICE(dev);
 
-    memory_region_init(&pbus->mmio, NULL, "platform bus", pbus->mmio_size);
+    memory_region_init(&pbus->mmio, OBJECT(dev), "platform bus",
+                       pbus->mmio_size);
     sysbus_init_mmio(d, &pbus->mmio);
 
     pbus->used_irqs = bitmap_new(pbus->num_irqs);