for toupper(), implicit function declaration
--- a/src/wminet.c
+++ b/src/wminet.c
@@ -20,6 +20,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <ctype.h>
 #include <unistd.h>
 #include <string.h>
 #include <signal.h>