diff --git a/attributs.py b/attributs.py
index d6e9d2a..37dcb83 100644
--- a/attributs.py
+++ b/attributs.py
@@ -648,7 +648,7 @@ class generalizedTimeFormat(Attr):
     une donnée de temps suivant la RFC 4517
 
     """
-    __slots__ = ("stamp", "datetime",)
+    __slots__ = ("datetime",)
     python_type = datetime.datetime
     default = datetime_from_generalized_time_format("19700101000000Z")
 
@@ -708,7 +708,6 @@ class generalizedTimeFormat(Attr):
             self.value = datetime_from_generalized_time_format(gtf)
         elif isinstance(gtf, datetime.datetime):
             self.value = gtf
-            self.stamp = from_generalized_time_format(self.value)
 
 @crans_attribute
 class debutAdhesion(generalizedTimeFormat):