diff --git a/pkgs/games/vassal/default.nix b/pkgs/games/vassal/default.nix
index fd3df36bdb51..4e8277b4592d 100644
--- a/pkgs/games/vassal/default.nix
+++ b/pkgs/games/vassal/default.nix
@@ -37,5 +37,6 @@ stdenv.mkDerivation rec {
       license = licenses.lgpl21Only;
       maintainers = with maintainers; [ tvestelind ];
       platforms = platforms.unix;
+      mainProgram = "vassal";
   };
 }