diff --git a/src/vendorcode/google/chromeos/acpi/amac.asl b/src/vendorcode/google/chromeos/acpi/amac.asl
index 51159f5124..c87862f6ff 100644
--- a/src/vendorcode/google/chromeos/acpi/amac.asl
+++ b/src/vendorcode/google/chromeos/acpi/amac.asl
@@ -42,6 +42,7 @@ Scope (\_SB)
 		/* Get "dock_passthru" value from RW_VPD */
 		Local0 = \VPD.VPDF ("RW", "dock_passthru")
 
+		Local1 = Zero
 		Switch (ToString (Local0))
 		{
 			Case ("ethernet_mac0") {
@@ -55,7 +56,7 @@ Scope (\_SB)
 				Local1 = \VPD.VPDF ("RO", "dock_mac")
 			}
 		}
-		If (!Local1) {
+		If (Local1 == Zero) {
 			Return (Zero)
 		}
 		Printf ("MAC address returned from VPD: %o", Local1)
diff --git a/src/vendorcode/google/chromeos/acpi/vpd.asl b/src/vendorcode/google/chromeos/acpi/vpd.asl
index 3b262f75a8..8f8b0e571d 100644
--- a/src/vendorcode/google/chromeos/acpi/vpd.asl
+++ b/src/vendorcode/google/chromeos/acpi/vpd.asl
@@ -139,7 +139,7 @@ Device (VPD)
 			Local1 <<= 7
 			Local1 |= Local2 & 0x7f
 		}
-		If (!Local1) {
+		If (Local1 == Zero) {
 			Return (Zero)
 		}
 
@@ -162,7 +162,7 @@ Device (VPD)
 	 */
 	Method (VPDS, 0, Serialized)
 	{
-		Name (VPKV, Package () { Zero, Zero })
+		Name (VPKV, Package () { "", "" })
 
 		/* Read the VPD type and ensure it is a string */
 		If (^VPRB () != ^VPES) {
@@ -193,14 +193,14 @@ Device (VPD)
 		/* End address of VPD region */
 		^VEND = ^VPTR + DerefOf (Local0[1])
 
-		If (!^VPTR || !^VEND) {
+		If (^VPTR == Zero || ^VEND == Zero) {
 			Printf ("Unable to find VPD region")
 			Return (Zero)
 		}
 
 		/* Verify VPD info header and save size */
 		Local0 = VVPD (^VPTR)
-		If (!Local0) {
+		If (Local0 == Zero) {
 			Printf ("VPD region %o did not verify", Arg0)
 			Return (Zero)
 		}
@@ -213,7 +213,7 @@ Device (VPD)
 		While (Local1 != ToString (Arg1)) {
 			Local2 = VPDS ()
 			Local1 = DerefOf (Local2[0])
-			If (!Local1) {
+			If (Local1 == "") {
 				Printf ("VPD KEY %o not found", Arg1)
 				Return (Zero)
 			}