diff --git a/paderbox/array/interval/core.py b/paderbox/array/interval/core.py
index d906f729..06d75bf8 100644
--- a/paderbox/array/interval/core.py
+++ b/paderbox/array/interval/core.py
@@ -195,7 +195,7 @@ class ArrayInterval:
     from_str = staticmethod(ArrayInterval_from_str)
     inverse_mode = False
 
-    def __init__(self, array, inverse_mode: bool = False):
+    def __init__(self, array, *, inverse_mode: bool = False):
         """
         The `ArrayInterval` is in many cases equivalent to a 1-dimensional
         boolean numpy array that stores activity information in an efficient