diff --git a/_config.yml b/_config.yml
index f941c3a..16a2efd 100644
--- a/_config.yml
+++ b/_config.yml
@@ -4,7 +4,7 @@ title: FEniCS Project
 description: Open-source finite element library
 fenicsversion: 2019.1.0
 fenicsversiondate: April 2019
-fenicsxversion: 0.10
+fenicsxversion: "0.10"
 dolfinxversion: 0.10.0.post1 # this is used in the URL of the Python demos
 fenicsxversiondate: October 2025