diff --git a/hw/sysbus.h b/hw/sysbus.h
index 899756bf7f..7b8ca236bf 100644
--- a/hw/sysbus.h
+++ b/hw/sysbus.h
@@ -8,7 +8,7 @@
 
 #define QDEV_MAX_MMIO 32
 #define QDEV_MAX_PIO 32
-#define QDEV_MAX_IRQ 256
+#define QDEV_MAX_IRQ 512
 
 typedef struct SysBusDevice SysBusDevice;