diff --git a/mdevaluate/reader.py b/mdevaluate/reader.py
index cc9471e..d6efecd 100755
--- a/mdevaluate/reader.py
+++ b/mdevaluate/reader.py
@@ -16,6 +16,7 @@ from array import array
 from zipfile import BadZipFile
 import builtins
 import warnings
+import subprocess
 
 import numpy as np
 import MDAnalysis as mdanalysis