diff --git a/src/errors.h b/src/errors.h
index e33f2e6..26629b0 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -3401,3 +3401,9 @@
 EXTERN char e_cannot_add_textprop_with_text_after_using_textprop_with_negative_id[]
 	INIT(= N_("E1339: Cannot add a textprop with text after using a textprop with a negative id"));
 #endif
+#ifdef FEAT_EVAL
+EXTERN char e_argument_already_declared_in_class_str[]
+	INIT(= N_("E1340: Argument already declared in the class: %s"));
+EXTERN char e_variable_already_declared_in_class_str[]
+	INIT(= N_("E1341: Variable already declared in the class: %s"));
+#endif