diff --git a/tools/power/acpi/os_specific/service_layers/osunixmap.c b/tools/power/acpi/os_specific/service_layers/osunixmap.c
index 3853a7350440094794a1fc9b93e3ec61afc30e84..0b1fa290245a904d3255d1fd84976baab2f09851 100644
--- a/tools/power/acpi/os_specific/service_layers/osunixmap.c
+++ b/tools/power/acpi/os_specific/service_layers/osunixmap.c
@@ -146,6 +146,6 @@ void acpi_os_unmap_memory(void *where, acpi_size length)
 	acpi_size page_size;
 
 	page_size = acpi_os_get_page_size();
-	offset = (acpi_physical_address) where % page_size;
+	offset = ACPI_TO_INTEGER(where) % page_size;
 	munmap((u8 *)where - offset, (length + offset));
 }