diff --git a/src/soc/intel/baytrail/acpi/southcluster.asl b/src/soc/intel/baytrail/acpi/southcluster.asl
index 31efcb9aeb..551bf08c7b 100644
--- a/src/soc/intel/baytrail/acpi/southcluster.asl
+++ b/src/soc/intel/baytrail/acpi/southcluster.asl
@@ -159,7 +159,7 @@ Method (_CRS, 0, Serialized)
 	{
 		Store (LPFW, LMIN)
 		Store (0x00100000, LLEN)
-		Subtract (LMIN + LLEN, One, LMAX)
+		LMAX = LMIN + LLEN - One
 	}
 	Else
 	{
diff --git a/src/superio/acpi/pnp.asl b/src/superio/acpi/pnp.asl
index dc5c3909c4..6fdcb85898 100644
--- a/src/superio/acpi/pnp.asl
+++ b/src/superio/acpi/pnp.asl
@@ -121,10 +121,10 @@
 
 #define PNP_WRITE_IRQ(IRQ_TO, RESOURCE, IRQ_TAG) \
 	CreateWordField (RESOURCE, IRQ_TAG._INT, IRQ_TAG##W)\
-	Subtract (FindSetLeftBit (IRQ_TAG##W), 1, IRQ_TO)
+	IRQ_TO = FindSetLeftBit (IRQ_TAG##W) - 1
 
 #define PNP_WRITE_DMA(DMA_TO, RESOURCE, DMA_TAG) \
 	CreateByteField (RESOURCE, DMA_TAG._DMA, DMA_TAG##W)\
-	Subtract (FindSetLeftBit (DMA_TAG##W), 1, DMA_TO)
+	DMA_TO = FindSetLeftBit (DMA_TAG##W) - 1
 
 #endif