diff --git a/km3io/offline.py b/km3io/offline.py
index 7dfffa1227c5e0ac26af0918239df4334f26af61..fa46b324d79e13d84311425833a71b4e67a8d090 100644
--- a/km3io/offline.py
+++ b/km3io/offline.py
@@ -1,6 +1,7 @@
 from collections import namedtuple
 import uproot
 import numpy as np
+import awkward1 as ak
 import warnings
 import km3io.definitions.trigger
 import km3io.definitions.fitparameters