diff --git a/MdePkg/Include/IndustryStandard/Pldm.h b/MdePkg/Include/IndustryStandard/Pldm.h
index c821f081f8..c2909dbd76 100644
--- a/MdePkg/Include/IndustryStandard/Pldm.h
+++ b/MdePkg/Include/IndustryStandard/Pldm.h
@@ -40,6 +40,7 @@ typedef struct  {
 typedef PLDM_MESSAGE_HEADER PLDM_REQUEST_HEADER;
 
 #define PLDM_MESSAGE_HEADER_IS_REQUEST        1
+#define PLDM_MESSAGE_HEADER_IS_RESPONSE       0
 #define PLDM_MESSAGE_HEADER_IS_DATAGRAM       1
 #define PLDM_MESSAGE_HEADER_INSTANCE_ID_MASK  0x1f