diff --git a/MdeModulePkg/Universal/HiiDatabaseDxe/ConfigKeywordHandler.c b/MdeModulePkg/Universal/HiiDatabaseDxe/ConfigKeywordHandler.c
index 96e05d4..6e79178 100644
--- a/MdeModulePkg/Universal/HiiDatabaseDxe/ConfigKeywordHandler.c
+++ b/MdeModulePkg/Universal/HiiDatabaseDxe/ConfigKeywordHandler.c
@@ -1987,7 +1987,7 @@
                    NULL
                    );
   if (BestLanguage == NULL) {
-    BestLanguage = AllocateCopyPool (AsciiStrLen ("en-US"), "en-US");
+    BestLanguage = AllocateCopyPool (sizeof ("en-US"), "en-US");
     ASSERT (BestLanguage != NULL);
   }