diff --git a/drivers/mtd/nand/fsl_upm.c b/drivers/mtd/nand/fsl_upm.c
index 071a60cb4204..ab06a5b514a9 100644
--- a/drivers/mtd/nand/fsl_upm.c
+++ b/drivers/mtd/nand/fsl_upm.c
@@ -302,7 +302,7 @@ static int __devinit fun_probe(struct of_device *ofdev,
 				  FSL_UPM_WAIT_WRITE_BYTE;
 
 	fun->io_base = devm_ioremap_nocache(&ofdev->dev, io_res.start,
-					    io_res.end - io_res.start + 1);
+					    resource_size(&io_res));
 	if (!fun->io_base) {
 		ret = -ENOMEM;
 		goto err2;