diff --git a/MdePkg/Library/UefiDebugLibConOut/DebugLibConstructor.c b/MdePkg/Library/UefiDebugLibConOut/DebugLibConstructor.c
index d4fdfbab55..8005370372 100644
--- a/MdePkg/Library/UefiDebugLibConOut/DebugLibConstructor.c
+++ b/MdePkg/Library/UefiDebugLibConOut/DebugLibConstructor.c
@@ -17,7 +17,7 @@
 //
 BOOLEAN     mPostEBS = FALSE;
 
-EFI_EVENT   mExitBootServicesEvent;
+static EFI_EVENT   mExitBootServicesEvent;
 
 //
 // Pointer to SystemTable