diff --git a/ete4/config.py b/ete4/config.py
index 4de6cb991..5a23000f2 100644
--- a/ete4/config.py
+++ b/ete4/config.py
@@ -11,7 +11,7 @@
 
 # Helper function to define global ETE_* variables.
 def ete_path(xdg_var, default):
-    return os.environ.get(xdg_var, os.environ['HOME'] + default) + '/ete'
+    return os.environ.get(xdg_var, os.path.expanduser('~') + default) + '/ete'
 
 ETE_DATA_HOME   = ete_path('XDG_DATA_HOME',   '/.local/share')
 ETE_CONFIG_HOME = ete_path('XDG_CONFIG_HOME', '/.config')
diff --git a/setup.py b/setup.py
index 20a4a2531..fb5d71555 100644
--- a/setup.py
+++ b/setup.py
@@ -1,13 +1,13 @@
 from setuptools import setup, Extension
 
 from glob import glob
-from os.path import isfile
+from os.path import isfile, sep
 
 from Cython.Build import cythonize
 
 
 def make_extension(path):  # to create cython extensions the way we want
-    name = path.replace('/', '.')[:-len('.pyx')]  # / -> .  and remove .pyx
+    name = path.replace(sep, '.')[:-len('.pyx')]  # / -> .  and remove .pyx
     return Extension(name, [path], extra_compile_args=['-O3'])
 
 setup(