diff --git a/pkgs/development/libraries/physics/fastnlo_toolkit/default.nix b/pkgs/development/libraries/physics/fastnlo_toolkit/default.nix
index d6cbe7cc4dd0..e4a731d31721 100644
--- a/pkgs/development/libraries/physics/fastnlo_toolkit/default.nix
+++ b/pkgs/development/libraries/physics/fastnlo_toolkit/default.nix
@@ -6,7 +6,7 @@
 , gfortran
 , lhapdf
 , ncurses
-, python
+, python ? null
 , swig
 , yoda
 , zlib