diff --git a/su.c b/su.c
index 736a2f3..6b0bac0 100644
--- a/su.c
+++ b/su.c
@@ -10,12 +10,16 @@
 #include <stdlib.h>
 #include "util.h"
 
+extern char **environ;
+
 static void
 usage(void)
 {
-	eprintf("usage: %s [username]\n", argv0);
+	eprintf("usage: %s [-l] [username]\n", argv0);
 }
 
+static int lflag = 0;
+
 int
 main(int argc, char **argv)
 {
@@ -27,6 +31,9 @@ main(int argc, char **argv)
 	int i;
 
 	ARGBEGIN {
+	case 'l':
+		lflag = 1;
+		break;
 	default:
 		usage();
 	} ARGEND;