diff --git a/MdePkg/Include/Protocol/SerialIo.h b/MdePkg/Include/Protocol/SerialIo.h
index e2e0c61eeb..16a865bfdc 100644
--- a/MdePkg/Include/Protocol/SerialIo.h
+++ b/MdePkg/Include/Protocol/SerialIo.h
@@ -17,6 +17,11 @@
     0xBB25CF6F, 0xF1D4, 0x11D2, {0x9A, 0x0C, 0x00, 0x90, 0x27, 0x3F, 0xC1, 0xFD } \
   }
 
+#define EFI_SERIAL_TERMINAL_DEVICE_TYPE_GUID \
+  { \
+    0X6AD9A60F, 0X5815, 0X4C7C, { 0X8A, 0X10, 0X50, 0X53, 0XD2, 0XBF, 0X7A, 0X1B } \
+  }
+
 ///
 /// Protocol GUID defined in EFI1.1.
 ///
@@ -299,5 +304,6 @@ struct _EFI_SERIAL_IO_PROTOCOL {
 };
 
 extern EFI_GUID gEfiSerialIoProtocolGuid;
+extern EFI_GUID gEfiSerialTerminalDeviceTypeGuid;
 
 #endif
diff --git a/MdePkg/MdePkg.dec b/MdePkg/MdePkg.dec
index d03fc5b49d..682e61cb88 100644
--- a/MdePkg/MdePkg.dec
+++ b/MdePkg/MdePkg.dec
@@ -670,6 +670,9 @@
   ## Include/Guid/RtPropertiesTable.h
   gEfiRtPropertiesTableGuid      = { 0xeb66918a, 0x7eef, 0x402a, { 0x84, 0x2e, 0x93, 0x1d, 0x21, 0xc3, 0x8a, 0xe9 }}
 
+  ## Include/Protocol/SerilaIo.h
+  gEfiSerialTerminalDeviceTypeGuid = { 0x6AD9A60F, 0x5815, 0x4C7C, { 0x8A, 0x10, 0x50, 0x53, 0xD2, 0xBF, 0x7A, 0x1B }}
+
   #
   # GUID defined in PI1.0
   #