diff -r ec49fc38bcb4 -r 91a1aa280326 src/ztfy/utils/timezone/__init__.py
--- a/src/ztfy/utils/timezone/__init__.py	Tue Apr 23 11:16:12 2013 +0200
+++ b/src/ztfy/utils/timezone/__init__.py	Tue May 07 15:41:57 2013 +0200
@@ -17,6 +17,7 @@
 
 # import standard packages
 import pytz
+from datetime import date
 
 # import Zope3 interfaces
 from zope.interface.common.idatetime import ITZInfo
@@ -48,6 +49,8 @@
 def tztime(value):
     if not value:
         return None
+    if isinstance(value, date):
+        return value
     if not value.tzinfo:
         value = GMT.localize(value)
     return value.astimezone(tzinfo())
@@ -56,6 +59,8 @@
 def gmtime(value):
     if not value:
         return None
+    if isinstance(value, date):
+        return value
     if not value.tzinfo:
         value = GMT.localize(value)
     return value.astimezone(GMT)