diff --git a/docs/requirements.txt b/docs/requirements.txt
index 6b6720af..2da170cd 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,2 +1,3 @@
 breathe==4.20
 jinja2==3.0.0
+sphinx_rtd_theme==2.0.0