diff --git a/libmat2/__init__.py b/libmat2/__init__.py
index dd51da9ddd66f5f6aca95f72c1dd8d20e9c3f4c1..f7b03fd168d26318f07d5a775d2c494d7c6bb30c 100644
--- a/libmat2/__init__.py
+++ b/libmat2/__init__.py
@@ -3,6 +3,7 @@
 import collections
 import enum
 import importlib
+import os
 from typing import Dict, Optional
 
 from . import subprocess