diff --git a/src/silx/gui/dialog/ColormapDialog.py b/src/silx/gui/dialog/ColormapDialog.py
index bd15604d25..1a1b62e61e 100644
--- a/src/silx/gui/dialog/ColormapDialog.py
+++ b/src/silx/gui/dialog/ColormapDialog.py
@@ -66,7 +66,7 @@
 import logging
 
 import numpy
-from typing import Union
+from future import __annotations__
 
 from .. import qt
 from .. import utils