diff --git a/src/southbridge/amd/cimx/sb800/acpi/fch.asl b/src/southbridge/amd/cimx/sb800/acpi/fch.asl
index 960cc15664..1e9ca640ca 100644
--- a/src/southbridge/amd/cimx/sb800/acpi/fch.asl
+++ b/src/southbridge/amd/cimx/sb800/acpi/fch.asl
@@ -22,11 +22,20 @@
 
 /* Operating System Capabilities Method */
 Method(_OSC,4)
-{	/* Check for proper PCI/PCIe UUID */
+{
+	// Create DWord-addressable fields from the Capabilities Buffer
+	CreateDWordField(Arg3,0,CDW1)
+	CreateDWordField(Arg3,4,CDW2)
+	CreateDWordField(Arg3,8,CDW3)
+
+	/* Check for proper PCI/PCIe UUID */
 	If(LEqual(Arg0,ToUUID("33DB4D5B-1FF7-401C-9657-7441C03DD766")))
 	{
 		/* Let OS control everything */
 		Return (Arg3)
+	} Else {
+		Or(CDW1,4,CDW1)	// Unrecognized UUID
+		Return(Arg3)
 	}
 }