diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 6037504fa7..2009dbc5fd 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -955,6 +955,8 @@
   # free pages for all of them. The page allocation for the type related to
   # cleared bits keeps the same as ususal.
   #
+  # This PCD is only valid if BIT0 and/or BIT2 are set in PcdHeapGuardPropertyMask.
+  #
   # Below is bit mask for this PCD: (Order is same as UEFI spec)<BR>
   #  EfiReservedMemoryType             0x0000000000000001<BR>
   #  EfiLoaderCode                     0x0000000000000002<BR>
@@ -984,6 +986,8 @@
   # if there's enough free memory for all of them. The pool allocation for the
   # type related to cleared bits keeps the same as ususal.
   #
+  # This PCD is only valid if BIT1 and/or BIT3 are set in PcdHeapGuardPropertyMask.
+  #
   # Below is bit mask for this PCD: (Order is same as UEFI spec)<BR>
   #  EfiReservedMemoryType             0x0000000000000001<BR>
   #  EfiLoaderCode                     0x0000000000000002<BR>
diff --git a/MdeModulePkg/MdeModulePkg.uni b/MdeModulePkg/MdeModulePkg.uni
index a6bcb627cf..9d2e473fa9 100644
--- a/MdeModulePkg/MdeModulePkg.uni
+++ b/MdeModulePkg/MdeModulePkg.uni
@@ -1171,6 +1171,7 @@
                                                                                         " before and after corresponding type of pages allocated if there's enough\n"
                                                                                         " free pages for all of them. The page allocation for the type related to\n"
                                                                                         " cleared bits keeps the same as ususal.\n\n"
+                                                                                        " This PCD is only valid if BIT0 and/or BIT2 are set in PcdHeapGuardPropertyMask.\n\n"
                                                                                         " Below is bit mask for this PCD: (Order is same as UEFI spec)<BR>\n"
                                                                                         "  EfiReservedMemoryType             0x0000000000000001\n"
                                                                                         "  EfiLoaderCode                     0x0000000000000002\n"
@@ -1198,6 +1199,7 @@
                                                                                         " before and after corresponding type of pages which the allocated pool occupies,\n"
                                                                                         " if there's enough free memory for all of them. The pool allocation for the\n"
                                                                                         " type related to cleared bits keeps the same as ususal.\n\n"
+                                                                                        " This PCD is only valid if BIT1 and/or BIT3 are set in PcdHeapGuardPropertyMask.\n\n"
                                                                                         " Below is bit mask for this PCD: (Order is same as UEFI spec)<BR>\n"
                                                                                         "  EfiReservedMemoryType             0x0000000000000001\n"
                                                                                         "  EfiLoaderCode                     0x0000000000000002\n"