diff --git a/EdkModulePkg/Bus/Pci/PciBus/Dxe/PciOptionRomSupport.c b/EdkModulePkg/Bus/Pci/PciBus/Dxe/PciOptionRomSupport.c
index 3ec76989a5..449d0dc443 100644
--- a/EdkModulePkg/Bus/Pci/PciBus/Dxe/PciOptionRomSupport.c
+++ b/EdkModulePkg/Bus/Pci/PciBus/Dxe/PciOptionRomSupport.c
@@ -64,7 +64,7 @@ Returns:
   PciRootBridgeIo = PciIoDevice->PciRootBridgeIo;
 
   //
-  // offset is 48 if is not ppb
+  // offset is 0x30 if is not ppb
   //
 
   //
@@ -112,15 +112,16 @@ Returns:
   if (EFI_ERROR (Status)) {
     return Status;
   }
-
-  AllOnes &= 0xFFFFFFFC;
-  if ((AllOnes == 0) || (AllOnes == 0xFFFFFFFC)) {
+  //
+  // Bits [1, 10] are reserved
+  //
+  AllOnes &= 0xFFFFF800;
+  if ((AllOnes == 0) || (AllOnes == 0xFFFFF800)) {
     return EFI_NOT_FOUND;
   }
 
   PciIoDevice->RomSize = (UINT64) ((~AllOnes) + 1);
   return EFI_SUCCESS;
-
 }
 
 EFI_STATUS