diff --git a/xcbgen/xtypes.py b/xcbgen/xtypes.py
index d72e6da..8125998 100644
--- a/xcbgen/xtypes.py
+++ b/xcbgen/xtypes.py
@@ -1,6 +1,8 @@
 '''
 This module contains the classes which represent XCB data types.
 '''
+from functools import reduce
+
 from .expr import Field, Expression
 from .align import Alignment, AlignmentLog
 from xml.etree.ElementTree import SubElement