diff --git a/pkgs/misc/screensavers/xautolock/default.nix b/pkgs/misc/screensavers/xautolock/default.nix
index f72fed624c04..c050454790d0 100644
--- a/pkgs/misc/screensavers/xautolock/default.nix
+++ b/pkgs/misc/screensavers/xautolock/default.nix
@@ -21,6 +21,7 @@ stdenv.mkDerivation rec {
     description = "A program that launches a given program when your X session has been idle for a given time.";
     homepage = http://www.ibiblio.org/pub/linux/X11/screensavers;
     maintainers = with maintainers; [ garbas ];
+    platforms = platforms.unix;
     license = licenses.gpl2;
   };
 }