diff --git a/guix/scripts/download.scm b/guix/scripts/download.scm
index b81295e5d9..6ebc14f573 100644
--- a/guix/scripts/download.scm
+++ b/guix/scripts/download.scm
@@ -96,6 +96,9 @@ Supported formats: 'nix-base32' (default), 'base32', and 'base16'
                 (lambda (opt name arg result)
                   (leave (_ "~A: unrecognized option~%") name))
                 (lambda (arg result)
+                  (when (assq 'argument result)
+                    (leave (_ "~A: extraneous argument~%") arg))
+
                   (alist-cons 'argument arg result))
                 %default-options))
 
diff --git a/tests/guix-download.sh b/tests/guix-download.sh
index 7af6f181f6..6283772c48 100644
--- a/tests/guix-download.sh
+++ b/tests/guix-download.sh
@@ -1,5 +1,5 @@
 # GNU Guix --- Functional package management for GNU
-# Copyright © 2012 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2012, 2015 Ludovic Courtès <ludo@gnu.org>
 #
 # This file is part of GNU Guix.
 #
@@ -34,3 +34,7 @@ then false; else true; fi
 
 # This one should succeed.
 guix download "file://$abs_top_srcdir/README"
+
+# This one should fail.
+if guix download "file:///does-not-exist" "file://$abs_top_srcdir/README"
+then false; else true; fi