diff --git a/setup.json b/setup.json
index 9cd8ff7c2e..d6abd3c338 100644
--- a/setup.json
+++ b/setup.json
@@ -73,6 +73,7 @@
             "docutils==0.15.2",
             "pygments~=2.5",
             "pydata-sphinx-theme~=0.4.0",
+            "markupsafe<2.1",
             "sphinx~=3.2.1",
             "sphinxcontrib-details-directive~=0.1.0",
             "sphinx-panels~=0.5.0",