diff --git a/OvmfPkg/Library/ResetSystemLib/ResetSystemLib.c b/OvmfPkg/Library/ResetSystemLib/ResetSystemLib.c
index 391d053347..6d149e84c2 100644
--- a/OvmfPkg/Library/ResetSystemLib/ResetSystemLib.c
+++ b/OvmfPkg/Library/ResetSystemLib/ResetSystemLib.c
@@ -27,7 +27,7 @@ AcpiPmControl (
 {
   ASSERT (SuspendType < 6);
 
-  IoBitFieldWrite16  (PcdGet16 (PcdAcpiPmBaseAddress) + 4, 10, 13, SuspendType);
+  IoBitFieldWrite16  (PcdGet16 (PcdAcpiPmBaseAddress) + 4, 10, 13, (UINT16) SuspendType);
   IoOr16 (PcdGet16 (PcdAcpiPmBaseAddress) + 4, BIT13);
   CpuDeadLoop ();
 }