diff --git a/pkgs/development/libraries/grib-api/default.nix b/pkgs/development/libraries/grib-api/default.nix
index 182f05a8ca89..1f7097dc4a3f 100644
--- a/pkgs/development/libraries/grib-api/default.nix
+++ b/pkgs/development/libraries/grib-api/default.nix
@@ -1,6 +1,6 @@
 { fetchurl, fetchpatch, lib, stdenv,
   cmake, netcdf, gfortran, libpng, openjpeg,
-  enablePython ? false, pythonPackages }:
+  enablePython ? false, pythonPackages ? null }:
 
 stdenv.mkDerivation rec {
   pname = "grib-api";