diff --git a/doc/requirements.txt b/doc/requirements.txt
index 8788d6ac3..218e06d1f 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -1,5 +1,5 @@
 #
 #
-sphinxcontrib-bibtex
+sphinxcontrib-bibtex<2.0.0
 #
 #