diff --git a/SecurityPkg/SecurityPkg.dec b/SecurityPkg/SecurityPkg.dec
index a91e3ea028..2c2153c19e 100644
--- a/SecurityPkg/SecurityPkg.dec
+++ b/SecurityPkg/SecurityPkg.dec
@@ -230,6 +230,10 @@
   ## GUID used to generate Spdm Uid
   gEfiDeviceSecuritySpdmUidGuid = {0xe37b5665, 0x5ef9, 0x4e7e, {0xb4, 0x91, 0xd6, 0x78, 0xab, 0xff, 0xfb, 0xcb }}
 
+  ## GUID used to tag the HOB indicating the TPM instance.
+  ## The GUIDed HOB contains the same value as PcdGetPtr (PcdTpmInstanceGuid).
+  gEdkiiTpmInstanceHobGuid           = { 0x4551b023, 0xba46, 0x4584, { 0x81, 0xcd, 0x4d, 0xe8, 0x61, 0xa7, 0x28, 0xbe } }
+
 [Ppis]
   ## The PPI GUID for that TPM physical presence should be locked.
   # Include/Ppi/LockPhysicalPresence.h