Backport from 8.18.1.16 snapshot

--- a/sendmail/arpadate.c
+++ b/sendmail/arpadate.c
@@ -167,7 +167,7 @@
 #endif /* TZ_TYPE == TZ_TZNAME */
 #if TZ_TYPE == TZ_TIMEZONE
 		{
-			extern char *timezone();
+			extern char *timezone __P((int, int));
 
 			tz = timezone(off, lt->tm_isdst);
 		}
--- a/sendmail/envelope.c
+++ b/sendmail/envelope.c
@@ -762,7 +762,7 @@
 #ifdef TTYNAME
 	static char ybuf[60];			/* holds tty id */
 	register char *p;
-	extern char *ttyname();
+	extern char *ttyname __P((int));
 #endif /* TTYNAME */
 
 	/*