diff --git a/book/index.adoc b/book/index.adoc
index c0286c9..b673ffb 100644
--- a/book/index.adoc
+++ b/book/index.adoc
@@ -117,9 +117,9 @@ use flake "git+https://code.oliverdavies.uk/opdavies/dev-shells#php84"
 This will install PHP 8.4, Composer and Phpactor without needing to create a bespoke `flake.nix`.
 
 [NOTE]
-===
+====
 If you're referencing a GitHub repository, you can use the shorter `github:username/repo` format instead of the full repository URL.
-===
+====
 
 [[what_flakes]]
 = What are Flakes?