diff --git a/hw/isa.h b/hw/isa.h
index 62e89d3..7a8874a 100644
--- a/hw/isa.h
+++ b/hw/isa.h
@@ -82,7 +82,7 @@
 
 static inline ISABus *isa_bus_from_device(ISADevice *d)
 {
-    return DO_UPCAST(ISABus, qbus, d->qdev.parent_bus);
+    return ISA_BUS(qdev_get_parent_bus(DEVICE(d)));
 }
 
 extern hwaddr isa_mem_base;