--- a/lib/Unix_util_stubs.c	2022-09-20 19:53:44.445778566 +0200
+++ b/lib/Unix_util_stubs.c	2022-09-20 19:54:03.521504343 +0200
@@ -24,6 +24,7 @@
   vincenzo_ml@yahoo.it
 */
 
+#include <unistd.h>
 #include <stddef.h>
 #include <string.h>
 #include <errno.h>