diff --git a/arch/powerpc/kernel/of_platform.c b/arch/powerpc/kernel/of_platform.c
index d501c23..d454f61 100644
--- a/arch/powerpc/kernel/of_platform.c
+++ b/arch/powerpc/kernel/of_platform.c
@@ -433,7 +433,7 @@
 	 * Note also that we don't do ISA, this will also be fixed with a
 	 * more massive rework.
 	 */
-	pci_setup_phb_io(phb, 0);
+	pci_setup_phb_io(phb, pci_io_base == 0);
 
 	/* Init pci_dn data structures */
 	pci_devs_phb_init_dynamic(phb);