--- tr-6.7/tr.c.orig	Sun May 10 10:14:40 2020
+++ tr-6.7/tr.c	Sun May 10 10:14:53 2020
@@ -32,6 +32,7 @@
 
 #include <sys/types.h>
 
+#include <getopt.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>