doc/features.rst | 4 ++--
 pyderasn.py      | 8 ++++++++

diff --git a/doc/features.rst b/doc/features.rst
index 04afdb53977f380846c480ff59fa2677bd2c9c24e7062a8dfc7aee17844ab51b..7829cf757550f51ff45d65467f7aa5829741a2ffb1823a000e843b332cf0089f 100644
--- a/doc/features.rst
+++ b/doc/features.rst
@@ -3,8 +3,8 @@ ========
 
 * BER/CER/DER decoding, DER encoding
 * Basic ASN.1 data types (X.208): BOOLEAN, INTEGER, BIT STRING, OCTET
-  STRING, NULL, OBJECT IDENTIFIER, ENUMERATED, all strings, UTCTime,
-  GeneralizedTime, CHOICE, ANY, SEQUENCE (OF), SET (OF)
+  STRING, NULL, OBJECT IDENTIFIER, ENUMERATED, all strings, UTCTime (no
+  BER), GeneralizedTime (no BER), CHOICE, ANY, SEQUENCE (OF), SET (OF)
 * Size :ref:`constraints <bounds>` checking
 * Working with sequences as high level data objects with ability to
   (un)marshall them
diff --git a/pyderasn.py b/pyderasn.py
index 6f29a26462f744550d1c2c07b3f6e04dbae57ed1582a753d567a2c684cfdf4d3..f92217397fdc5fd559003b252719f3ef8745fd1ecd693540697efa6302d00d16 100755
--- a/pyderasn.py
+++ b/pyderasn.py
@@ -3661,6 +3661,10 @@     >>> t.todatetime()
     datetime.datetime(2017, 9, 30, 22, 7, 50)
     >>> UTCTime(datetime(2057, 9, 30, 22, 7, 50)).todatetime()
     datetime.datetime(1957, 9, 30, 22, 7, 50)
+
+    .. warning::
+
+       No BER encodings are supported. Only DER.
     """
     __slots__ = ()
     tag_default = tag_encode(23)
@@ -3811,6 +3815,10 @@     >>> str(t)
     '20170930220750.000123Z'
     >>> t = GeneralizedTime(datetime(2057, 9, 30, 22, 7, 50))
     GeneralizedTime GeneralizedTime 2057-09-30T22:07:50
+
+    .. warning::
+
+       No BER encodings are supported. Only DER.
 
     .. warning::