diff --git a/src/errors.h b/src/errors.h
index 34a0d58..a116505 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -3552,7 +3552,8 @@
 	INIT(= N_("E1393: Type can only be defined in Vim9 script"));
 EXTERN char e_type_name_must_start_with_uppercase_letter_str[]
 	INIT(= N_("E1394: Type name must start with an uppercase letter: %s"));
-// E1395 unused
+EXTERN char e_using_null_class[]
+	INIT(= N_("E1395: Using a null class"));
 EXTERN char e_typealias_already_exists_for_str[]
 	INIT(= N_("E1396: Type alias \"%s\" already exists"));
 EXTERN char e_missing_typealias_name[]