diff --git a/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c b/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
index 6d46fd1e36..dfb21673fd 100644
--- a/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
+++ b/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
@@ -2545,7 +2545,11 @@ HiiGetFontInfo (
       goto Exit;
     }
   }
-
+  
+  //
+  // StringInfoIn must not be NULL if it is not system default font info.
+  //
+  ASSERT (StringInfoIn != NULL);
   //
   // Check the font information mask to make sure it is valid.
   //