diff --git a/tester_MITDB.py b/tester_MITDB.py
index 1be03bb..5fb36d2 100644
--- a/tester_MITDB.py
+++ b/tester_MITDB.py
@@ -1,6 +1,7 @@
 import numpy as np
 import pandas as pd
 import _tester_utils
+import wfdb
 import pathlib
 import os
 from ecgdetectors import Detectors