diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 39a7bb32aa..208c16f450 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -483,7 +483,7 @@ static void pci_bus_uninit(PCIBus *bus)
     pci_host_bus_unregister(BUS(bus)->parent);
 }
 
-bool pci_bus_is_express(PCIBus *bus)
+bool pci_bus_is_express(const PCIBus *bus)
 {
     return object_dynamic_cast(OBJECT(bus), TYPE_PCIE_BUS);
 }
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index 85ee458cd2..d5a40cd058 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -270,7 +270,7 @@ typedef void (*pci_bus_dev_fn)(PCIBus *b, PCIDevice *d, void *opaque);
 typedef void (*pci_bus_fn)(PCIBus *b, void *opaque);
 typedef void *(*pci_bus_ret_fn)(PCIBus *b, void *opaque);
 
-bool pci_bus_is_express(PCIBus *bus);
+bool pci_bus_is_express(const PCIBus *bus);
 
 void pci_root_bus_init(PCIBus *bus, size_t bus_size, DeviceState *parent,
                        const char *name,