diff --git a/arch/powerpc/sysdev/mpic_msgr.c b/arch/powerpc/sysdev/mpic_msgr.c
index eb69a5186243..280e964e1aa8 100644
--- a/arch/powerpc/sysdev/mpic_msgr.c
+++ b/arch/powerpc/sysdev/mpic_msgr.c
@@ -196,7 +196,7 @@ static int mpic_msgr_probe(struct platform_device *dev)
 
 	/* IO map the message register block. */
 	of_address_to_resource(np, 0, &rsrc);
-	msgr_block_addr = ioremap(rsrc.start, rsrc.end - rsrc.start);
+	msgr_block_addr = ioremap(rsrc.start, resource_size(&rsrc));
 	if (!msgr_block_addr) {
 		dev_err(&dev->dev, "Failed to iomap MPIC message registers");
 		return -EFAULT;