diff --git a/hw/char/serial.c b/hw/char/serial.c
index 9298881af9..2ab8b69e03 100644
--- a/hw/char/serial.c
+++ b/hw/char/serial.c
@@ -997,7 +997,7 @@ static void serial_io_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    memory_region_init_io(&s->io, NULL, &serial_io_ops, s, "serial", 8);
+    memory_region_init_io(&s->io, OBJECT(dev), &serial_io_ops, s, "serial", 8);
     sysbus_init_mmio(SYS_BUS_DEVICE(sio), &s->io);
     sysbus_init_irq(SYS_BUS_DEVICE(sio), &s->irq);
 }
@@ -1106,8 +1106,9 @@ static void serial_mm_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    memory_region_init_io(&s->io, NULL, &serial_mm_ops[smm->endianness], smm,
-                          "serial", 8 << smm->regshift);
+    memory_region_init_io(&s->io, OBJECT(dev),
+                          &serial_mm_ops[smm->endianness], smm, "serial",
+                          8 << smm->regshift);
     sysbus_init_mmio(SYS_BUS_DEVICE(smm), &s->io);
     sysbus_init_irq(SYS_BUS_DEVICE(smm), &smm->serial.irq);
 }