diff --git a/src/errors.h b/src/errors.h
index e71b706..47e9876 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -341,3 +341,5 @@
 	INIT(= N_("E1151: Mismatched endfunction"));
 EXTERN char e_mismatched_enddef[]
 	INIT(= N_("E1152: Mismatched enddef"));
+EXTERN char e_invalid_operation_for_bool[]
+	INIT(= N_("E1153: Invalid operation for bool"));