diff --git a/max.c b/max.c
--- a/max.c
+++ b/max.c
@@ -18,7 +18,7 @@
 
     if (argc != 3) {
         printf ("Usage: %s value1 value2\n", argv[0]);
-        return EXIT_SUCCESS;
+        return EXIT_FAILURE;
     }
     a = atoi (argv[1]);
     b = atoi (argv[2]);