diff --git a/pkgs/development/python-modules/pytorch/default.nix b/pkgs/development/python-modules/pytorch/default.nix
index 0b2525abfeb1..22a87b386e18 100644
--- a/pkgs/development/python-modules/pytorch/default.nix
+++ b/pkgs/development/python-modules/pytorch/default.nix
@@ -1,5 +1,5 @@
 { stdenv, lib, fetchFromGitHub, fetchpatch, buildPythonPackage, python,
-  cudaSupport ? false, cudatoolkit ? null, cudnn ? null, nccl ? null, magma ? null,
+  cudaSupport ? false, cudatoolkit, cudnn, nccl, magma,
   mklDnnSupport ? true, useSystemNccl ? true,
   MPISupport ? false, mpi,
   buildDocs ? false,
@@ -30,8 +30,6 @@
   isPy3k, pythonOlder }:
 
 # assert that everything needed for cuda is present and that the correct cuda versions are used
-assert !cudaSupport || cudatoolkit != null;
-assert cudnn == null || cudatoolkit != null;
 assert !cudaSupport || (let majorIs = lib.versions.major cudatoolkit.version;
                         in majorIs == "9" || majorIs == "10" || majorIs == "11");