diff --git a/src/pya/pya/pya.cc b/src/pya/pya/pya.cc
index 0361b0755..2310cf9b6 100644
--- a/src/pya/pya/pya.cc
+++ b/src/pya/pya/pya.cc
@@ -251,8 +251,9 @@ PythonInterpreter::PythonInterpreter (bool embedded)
 
   if (! has_klayout_pythonhome) {
 
-    //  Use our own installation path for PYTHOHOME unless given
-    Py_SetPythonHome (tl::to_wstring (inst_dir).c_str ());
+    //  Use our own installation path for PYTHONHOME unless given
+    //  (Our Windows installation comes with its own copy of the libraries)
+    tl::set_env (pythonhome_name, inst_dir);
 
   }
 
diff --git a/testdata/lym/m2.py b/testdata/lym/m2.py
index 401d57365..ca794598c 100644
--- a/testdata/lym/m2.py
+++ b/testdata/lym/m2.py
@@ -1,6 +1,7 @@
 
 import os
 import inspect
+import pya
 
 def lineno():
   return inspect.currentframe().f_back.f_lineno