diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
index df67c78..93a7c08 100644
--- a/include/linux/pci-acpi.h
+++ b/include/linux/pci-acpi.h
@@ -15,7 +15,7 @@
 {
 	struct pci_bus *pbus = pdev->bus;
 	/* Find a PCI root bus */
-	while (pbus->parent)
+	while (!pci_is_root_bus(pbus))
 		pbus = pbus->parent;
 	return acpi_get_pci_rootbridge_handle(pci_domain_nr(pbus),
 					      pbus->number);