diff -Naur libgpg-error-1.42/src/mkerrcodes.c libgpg-error-1.42.serenity/src/mkerrcodes.c
--- libgpg-error-1.42/src/mkerrcodes.c	2016-11-16 13:22:03.000000000 +0100
+++ libgpg-error-1.42.serenity/src/mkerrcodes.c	2021-04-14 01:38:44.112242487 +0200
@@ -22,6 +22,7 @@
    system, while this file will be run on the build system.  */
 
 #include <stdio.h>
+#include <errno.h>
 
 #include "mkerrcodes.h"