diff --git a/pkgs/development/python-modules/ifcopenshell/default.nix b/pkgs/development/python-modules/ifcopenshell/default.nix
index 37988bb8452e..09a67f05d542 100644
--- a/pkgs/development/python-modules/ifcopenshell/default.nix
+++ b/pkgs/development/python-modules/ifcopenshell/default.nix
@@ -130,7 +130,7 @@ buildPythonPackage rec {
 
   pythonImportsCheck = [ "ifcopenshell" ];
 
-  PYTHONUSERBASE = ".";
+  env.PYTHONUSERBASE = ".";
 
   # We still build with python to generate ifcopenshell_wrapper.py and ifcopenshell_wrapper.so
   cmakeFlags = [