diff --git a/src/mainboard/aopen/dxplplusu/acpi/e7505_pri.asl b/src/mainboard/aopen/dxplplusu/acpi/e7505_pri.asl
index 7216d33a21..29a81707a8 100644
--- a/src/mainboard/aopen/dxplplusu/acpi/e7505_pri.asl
+++ b/src/mainboard/aopen/dxplplusu/acpi/e7505_pri.asl
@@ -52,7 +52,7 @@ Device (MBRS)
 		Decrement (Local1)
 		If (LGreater (Local1, 0x10))
 		{
-			Subtract (Local1, 0x0F, Local1)
+			Local1 -= 0x0F
 			Store (ShiftLeft (Local1, 0x14), MEM2)
 			Store (0x01000000, MS00)
 			Store (MS00, MS01)
diff --git a/src/mainboard/aopen/dxplplusu/acpi/e7505_sec.asl b/src/mainboard/aopen/dxplplusu/acpi/e7505_sec.asl
index 0ba808d255..400a5d7092 100644
--- a/src/mainboard/aopen/dxplplusu/acpi/e7505_sec.asl
+++ b/src/mainboard/aopen/dxplplusu/acpi/e7505_sec.asl
@@ -44,8 +44,8 @@ Method (_CRS, 0, NotSerialized)
 	And (\_SB.PCI0.TOLM, 0xF800, Local1)
 	ShiftRight (Local1, 0x04, Local1)
 	ShiftLeft (Local1, 0x14, MEML)
-	Subtract (IO_APIC_ADDR, 0x01, MEMH)
-	Subtract (IO_APIC_ADDR, MEML, LENM)
+	MEMH = IO_APIC_ADDR - 1
+	LENM = IO_APIC_ADDR - MEML
 
 	Return (PBRS)
 }