diff --git a/MdePkg/Library/UefiDebugLibStdErr/DebugLib.c b/MdePkg/Library/UefiDebugLibStdErr/DebugLib.c
index 40eb697e7e..fcfdafede0 100644
--- a/MdePkg/Library/UefiDebugLibStdErr/DebugLib.c
+++ b/MdePkg/Library/UefiDebugLibStdErr/DebugLib.c
@@ -106,9 +106,9 @@ DebugPrintMarker (
     // Convert the DEBUG() message to a Unicode String
     //
     if (BaseListMarker == NULL) {
-      UnicodeVSPrintAsciiFormat (Buffer, MAX_DEBUG_MESSAGE_LENGTH, Format, VaListMarker);
+      UnicodeVSPrintAsciiFormat (Buffer, sizeof (Buffer), Format, VaListMarker);
     } else {
-      UnicodeBSPrintAsciiFormat (Buffer, MAX_DEBUG_MESSAGE_LENGTH, Format, BaseListMarker);
+      UnicodeBSPrintAsciiFormat (Buffer, sizeof (Buffer), Format, BaseListMarker);
     }
 
     //