diff --git a/pkgs/applications/science/physics/sherpa/default.nix b/pkgs/applications/science/physics/sherpa/default.nix
index 858064a8d22..ba519cc2d03 100644
--- a/pkgs/applications/science/physics/sherpa/default.nix
+++ b/pkgs/applications/science/physics/sherpa/default.nix
@@ -23,6 +23,7 @@ stdenv.mkDerivation rec {
     "--enable-fastjet=${fastjet}"
     "--enable-lhapdf=${lhapdf}"
     "--enable-rivet=${rivet}"
+    "--enable-pythia"
   ];
 
   meta = with lib; {