diff --git a/ap.in b/ap.in
index 32e2fc4..bcc5ab7 100755
--- a/ap.in
+++ b/ap.in
@@ -103,7 +103,7 @@ subcmd.builddirs = {
 
 
 function print_usage()
-	io.write("usage: ap SUBCOMMAND [options]\n\nSubcommands are:\n")
+	io.write("usage: ap -d <DIR> SUBCOMMAND [options]\n\nSubcommands are:\n")
 	local k,v
 	for k in pairs(subcmd) do
 		print("  "..k)