diff --git a/pkgs/development/python-modules/pyfakefs/default.nix b/pkgs/development/python-modules/pyfakefs/default.nix
index e453a787ac13..a1427188b22d 100644
--- a/pkgs/development/python-modules/pyfakefs/default.nix
+++ b/pkgs/development/python-modules/pyfakefs/default.nix
@@ -11,7 +11,6 @@
   # tests
   pandas,
   pytestCheckHook,
-  undefined,
 }:
 
 buildPythonPackage rec {
@@ -33,7 +32,6 @@ buildPythonPackage rec {
   nativeCheckInputs = [
     pandas
     pytestCheckHook
-    undefined
   ];
 
   pytestFlagsArray = [