diff --git a/arch/powerpc/sysdev/cpm2_common.c b/arch/powerpc/sysdev/cpm2_common.c
index 9244129747955d062b7a255c3797b97a23b88ab4..c827715a50907704ad1e7d4b65d7206fa9988477 100644
--- a/arch/powerpc/sysdev/cpm2_common.c
+++ b/arch/powerpc/sysdev/cpm2_common.c
@@ -102,7 +102,7 @@ cpm_setbrg(uint brg, uint rate)
 		brg -= 4;
 	}
 	bp += brg;
-	*bp = ((BRG_UART_CLK / rate) << 1) | CPM_BRG_EN;
+	out_be32(bp, (((BRG_UART_CLK / rate) - 1) << 1) | CPM_BRG_EN);
 
 	cpm2_unmap(bp);
 }