diff --git a/pkgs/misc/screensavers/vlock/default.nix b/pkgs/misc/screensavers/vlock/default.nix
index 1602c94c0992..c156373f1481 100644
--- a/pkgs/misc/screensavers/vlock/default.nix
+++ b/pkgs/misc/screensavers/vlock/default.nix
@@ -26,5 +26,6 @@ stdenv.mkDerivation rec {
     license = licenses.gpl2;
     maintainers = [ ];
     platforms = platforms.linux;
+    mainProgram = "vlock";
   };
 }