diff --git a/docs/requirements.txt b/docs/requirements.txt
index c05e89e5f..68576428c 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -2,3 +2,4 @@ sphinx==3.2.1
 sphinx_rtd_theme
 recommonmark==0.7.1
 sphinx-markdown-tables
+Pygments==2.6.1