diff --git a/README.rst b/README.rst
index 31920a3c3bff5f038d1142e74dd0aeca4e2a0f26..31bb096a83c83733e3e9ab477d0ee91019d5a9e9 100644
--- a/README.rst
+++ b/README.rst
@@ -78,6 +78,7 @@ at: https://www.shore.co.il/git/.
 TODO
 ----
 
+- Add unit tests of filters using doctest.
 - Fix combining dictionaries test.
 - Fix Travis CI test on Python 3.2 (https://travis-ci.org/adarnimrod/template/jobs/187388235).
 - Release on tagged commits to PyPI in Travis CI