diff --git a/cpu/mpc83xx/pci.c b/cpu/mpc83xx/pci.c
index 5b8eeb7758b2122d4d3d0a47242f21677f7312cf..ab0760bce65d584cc78cbebb79e1ab89df976a18 100644
--- a/cpu/mpc83xx/pci.c
+++ b/cpu/mpc83xx/pci.c
@@ -83,7 +83,7 @@ static void pci_init_bus(int bus, struct pci_region *reg)
 	pci_ctrl->pibar1 = 0;
 	pci_ctrl->piebar1 = 0;
 	pci_ctrl->piwar1 = PIWAR_EN | PIWAR_PF | PIWAR_RTT_SNOOP |
-	                   PIWAR_WTT_SNOOP | (__ilog2(gd->ram_size) - 1);
+	                   PIWAR_WTT_SNOOP | (__ilog2(gd->ram_size - 1));
 
 	i = hose->region_count++;
 	hose->regions[i].bus_start = 0;