diff --git a/gwinc/nb.py b/gwinc/nb.py
index f3a454144bfd38275c02b4d32c8a17f8c0dafe17..40e7477cc5ce12a1e997d8ccfd9bb248b31515b4 100644
--- a/gwinc/nb.py
+++ b/gwinc/nb.py
@@ -1,8 +1,5 @@
-import os
 import operator
 import itertools
-import importlib
-import importlib.util
 import collections
 import numpy as np
 import scipy.interpolate