diff --git a/pkgs/applications/window-managers/sway/lock-effects.nix b/pkgs/applications/window-managers/sway/lock-effects.nix
index 6f1f337d23ee..b3bb8f772f7a 100644
--- a/pkgs/applications/window-managers/sway/lock-effects.nix
+++ b/pkgs/applications/window-managers/sway/lock-effects.nix
@@ -44,6 +44,7 @@ stdenv.mkDerivation rec {
     longDescription = ''
       Swaylock, with fancy effects
     '';
+    mainProgram = "swaylock";
     inherit (src.meta) homepage;
     license = licenses.mit;
     platforms = platforms.linux;