--- a/src/xneur.c
+++ b/src/xneur.c
@@ -404,6 +404,11 @@
 		}
 	}
 
+	if (optind < argc)
+	{
+		xneur_usage();
+		exit(EXIT_FAILURE);
+	}
 	if (opted)
 		exit(EXIT_SUCCESS);
 }