diff --git a/src/roiextractors/volumetricimagingextractor.py b/src/roiextractors/volumetricimagingextractor.py
index 5f1909c3..4c638c12 100644
--- a/src/roiextractors/volumetricimagingextractor.py
+++ b/src/roiextractors/volumetricimagingextractor.py
@@ -1,6 +1,6 @@
 """Base class definition for volumetric imaging extractors."""
 
-from typing import Tuple, List, Iterable, Optional, Union
+from typing import Tuple, List, Iterable, Optional
 import numpy as np
 
 from .extraction_tools import ArrayType, DtypeType