diff --git a/doc/requirements.txt b/doc/requirements.txt
index 9faabffb9b..39981d4e88 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -9,7 +9,7 @@ future
 requests
 pysb
 pandas
-rdflib==4.2.1
+rdflib
 jinja2
 protmapper
 pyyaml