diff --git a/pkgs/misc/screensavers/xss-lock/default.nix b/pkgs/misc/screensavers/xss-lock/default.nix
index ec7e8f4e7e5c..88b4b6b795f3 100644
--- a/pkgs/misc/screensavers/xss-lock/default.nix
+++ b/pkgs/misc/screensavers/xss-lock/default.nix
@@ -18,6 +18,7 @@ stdenv.mkDerivation {
   meta = with lib; {
     description = "Use external locker (such as i3lock) as X screen saver";
     license = licenses.mit;
+    mainProgram = "xss-lock";
     maintainers = with maintainers; [ malyn offline ];
     platforms = platforms.linux;
   };