diff --git a/hw/core/bus.c b/hw/core/bus.c
index ad0c9df335..4651f24486 100644
--- a/hw/core/bus.c
+++ b/hw/core/bus.c
@@ -102,6 +102,7 @@ static void qbus_realize(BusState *bus, DeviceState *parent, const char *name)
         QLIST_INSERT_HEAD(&bus->parent->child_bus, bus, sibling);
         bus->parent->num_child_bus++;
         object_property_add_child(OBJECT(bus->parent), bus->name, OBJECT(bus), NULL);
+        object_unref(OBJECT(bus));
     } else if (bus != sysbus_get_default()) {
         /* TODO: once all bus devices are qdevified,
            only reset handler for main_system_bus should be registered here. */
diff --git a/hw/usb/dev-smartcard-reader.c b/hw/usb/dev-smartcard-reader.c
index fa546fb3ce..13d0befd9c 100644
--- a/hw/usb/dev-smartcard-reader.c
+++ b/hw/usb/dev-smartcard-reader.c
@@ -1147,7 +1147,6 @@ static void ccid_unrealize(USBDevice *dev, Error **errp)
     USBCCIDState *s = USB_CCID_DEV(dev);
 
     ccid_bulk_in_clear(s);
-    object_unref(OBJECT(&s->bus));
 }
 
 static void ccid_flush_pending_answers(USBCCIDState *s)
diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
index 47b992f403..c99398b7f6 100644
--- a/hw/usb/dev-storage.c
+++ b/hw/usb/dev-storage.c
@@ -588,13 +588,6 @@ static const struct SCSIBusInfo usb_msd_scsi_info_bot = {
     .load_request = usb_msd_load_request,
 };
 
-static void usb_msd_unrealize_storage(USBDevice *dev, Error **errp)
-{
-    MSDState *s = USB_STORAGE_DEV(dev);
-
-    object_unref(OBJECT(&s->bus));
-}
-
 static void usb_msd_storage_realize(USBDevice *dev, Error **errp)
 {
     MSDState *s = USB_STORAGE_DEV(dev);
@@ -642,13 +635,6 @@ static void usb_msd_storage_realize(USBDevice *dev, Error **errp)
     s->scsi_dev = scsi_dev;
 }
 
-static void usb_msd_bot_unrealize(USBDevice *dev, Error **errp)
-{
-    MSDState *s = USB_STORAGE_DEV(dev);
-
-    object_unref(OBJECT(&s->bus));
-}
-
 static void usb_msd_bot_realize(USBDevice *dev, Error **errp)
 {
     MSDState *s = USB_STORAGE_DEV(dev);
@@ -712,7 +698,6 @@ static void usb_msd_class_storage_initfn(ObjectClass *klass, void *data)
     USBDeviceClass *uc = USB_DEVICE_CLASS(klass);
 
     uc->realize = usb_msd_storage_realize;
-    uc->unrealize = usb_msd_unrealize_storage;
     dc->props = msd_properties;
 }
 
@@ -775,7 +760,6 @@ static void usb_msd_class_bot_initfn(ObjectClass *klass, void *data)
     USBDeviceClass *uc = USB_DEVICE_CLASS(klass);
 
     uc->realize = usb_msd_bot_realize;
-    uc->unrealize = usb_msd_bot_unrealize;
     uc->attached_settable = true;
 }
 
diff --git a/hw/usb/dev-uas.c b/hw/usb/dev-uas.c
index aaf5a88095..be566cad02 100644
--- a/hw/usb/dev-uas.c
+++ b/hw/usb/dev-uas.c
@@ -896,8 +896,6 @@ static void usb_uas_unrealize(USBDevice *dev, Error **errp)
     UASDevice *uas = USB_UAS(dev);
 
     qemu_bh_delete(uas->status_bh);
-
-    object_unref(OBJECT(&uas->bus));
 }
 
 static void usb_uas_realize(USBDevice *dev, Error **errp)