diff --git a/drivers/acpi/atomicio.c b/drivers/acpi/atomicio.c
index 7489b89c300fc3b0ab2f0a55c2bc09ead5e2c738..f151afe61aabca96f17bb92dfdbc7e855ad08620 100644
--- a/drivers/acpi/atomicio.c
+++ b/drivers/acpi/atomicio.c
@@ -76,7 +76,7 @@ static void __iomem *__acpi_ioremap_fast(phys_addr_t paddr,
 {
 	struct acpi_iomap *map;
 
-	map = __acpi_find_iomap(paddr, size);
+	map = __acpi_find_iomap(paddr, size/8);
 	if (map)
 		return map->vaddr + (paddr - map->paddr);
 	else