diff --git a/docs/manpage.rst b/docs/manpage.rst
index 170f43cd24e49477f4c241b592ede6c9ed23e304..971f8e1cea3ef7a13366d0aa90bdb56b6901115d 100644
--- a/docs/manpage.rst
+++ b/docs/manpage.rst
@@ -29,7 +29,8 @@ options
 ``positional arguments``:
 
   FILE
-    input wordlist. ``'-'`` will read from stdin.
+    optional input wordlist. ``'-'`` will read from stdin. Should contain one
+    word per line.
 
 ``optional arguments``: