diff --git a/tests/requirements-libraries.txt b/tests/requirements-libraries.txt
index a32b58f61a6..8d0a710144b 100644
--- a/tests/requirements-libraries.txt
+++ b/tests/requirements-libraries.txt
@@ -19,7 +19,7 @@ gevent
 
 pygments
 pylint>=1.5
-markdown
+markdown==2.6.8
 simplejson # simplejson is used for text_c_extension
 
 # sphinx 1.5 requires Python 2.7 or >= 3.4