diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
index e86516ff8f4b..f5c9504f6071 100644
--- a/arch/powerpc/include/asm/io.h
+++ b/arch/powerpc/include/asm/io.h
@@ -46,7 +46,7 @@ extern struct pci_dev *isa_bridge_pcidev;
  * define properly based on the platform
  */
 #ifndef CONFIG_PCI
-#define _IO_BASE	0
+#define _IO_BASE	POISON_POINTER_DELTA
 #define _ISA_MEM_BASE	0
 #define PCI_DRAM_OFFSET 0
 #elif defined(CONFIG_PPC32)