diff --git a/lang/CZ.py b/lang/CZ.py
new file mode 100644
index 0000000..2dc25d8
--- /dev/null
+++ b/lang/CZ.py
@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+
+#    callirhoe - high quality calendar rendering
+#    Copyright (C) 2012 George M. Tzoumas
+
+""" Czech language definition file"""
+#    Copyright (C) 2021 Petr Michalik
+
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation, either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see http://www.gnu.org/licenses/
+
+long_day_name = [ u'Pondělí', u'Úterý', u'Středa',
+             u'Čtvrtek', u'Pátek', u'Sobota', u'Neděle' ]
+
+short_day_name = [ u'Po', u'Út', u'St', u'Čt', u'Pá', u'So', u'Ne' ]
+
+long_month_name = [ '',
+               u'Leden', u'Únor', u'Březen', u'Duben',
+               u'Květen', u'Červen', u'Červenec', u'Srpen',
+               u'Září', u'Říjen', u'Listopad', u'Prosinec' ]
+
+short_month_name = [ '',
+               u'Led', u'Úno', u'Bře', u'Dub', u'Kvě', u'Čer',
+               u'Čvc', u'Srp', u'Zář', u'Říj', u'Lis', u'Pro' ]
+
+week_of_year_prefix = u'T'