diff --git a/km3io/tools.py b/km3io/tools.py
index c4c157a722fddd6954c484f306ea45b46446b99d..c4b6c0dd95e5e0f43c80da1516ebf160481928db 100644
--- a/km3io/tools.py
+++ b/km3io/tools.py
@@ -162,6 +162,7 @@ def fitinf(fitparam, tracks):
 
     return out
 
+
 def count_nested(arr, axis=0):
     """Count elements in a nested awkward Array.