--- crc.c.orig	Sun May  2 19:14:18 1993
+++ crc.c	Thu May 20 19:50:25 1999
@@ -117,6 +117,10 @@
 {
 	register errors = 0;
 
+	if(argc	< 2) {
+		fprintf(stderr, "Usage: %s [-x] [-k] file ...\n", argv[0]);
+		exit(0);
+	}
 	if (! strcmp(argv[1], "-x")) {
 		Block = 128; --argc; ++argv;
 	}
