diff --git a/product/ERP5Type/patches/DateTimePatch.py b/product/ERP5Type/patches/DateTimePatch.py
index 5f6df3a274b8843d7fbf0d330518a2bd0a638a0d..16f8e1c7364937e339dec9fd88b5676af895ef6f 100644
--- a/product/ERP5Type/patches/DateTimePatch.py
+++ b/product/ERP5Type/patches/DateTimePatch.py
@@ -28,22 +28,12 @@
 
 from DateTime import DateTime as DateTimeKlass
 import math
-from DateTime.DateTime import _calcSD, _calcDependentSecond, _calcYMDHMS, getDefaultDateFormat, _correctYear, _calcHMS, _calcDependentSecond2
+from DateTime.DateTime import _calcSD, _calcDependentSecond, _calcYMDHMS,\
+getDefaultDateFormat, _correctYear, _calcHMS, _calcDependentSecond2, DateTimeError,\
+SyntaxError, DateError, TimeError
 
 STATE_KEY = 'str'
 
-class DateTimeError( Exception ):
-    pass
-
-class SyntaxError( DateTimeError ):
-    pass
-
-class DateError( DateTimeError ):
-    pass
-
-class TimeError( DateTimeError ):
-    pass
-
 def DateTime__setstate__(self, state):
   if isinstance(state, tuple):
     t, tz = state