diff --git a/Doc/requirements-oldest-sphinx.txt b/Doc/requirements-oldest-sphinx.txt
index f7e0665bde445d..501a360622d42a 100644
--- a/Doc/requirements-oldest-sphinx.txt
+++ b/Doc/requirements-oldest-sphinx.txt
@@ -21,7 +21,7 @@ certifi==2022.12.7
 charset-normalizer==3.1.0
 colorama==0.4.6
 docutils==0.16
-idna==3.4
+idna==3.15
 imagesize==1.4.1
 Jinja2==2.11.3
 MarkupSafe==1.1.1