diff --git a/tools/update-reveal.R b/tools/update-reveal.R
index 3be6803..5d13db9 100644
--- a/tools/update-reveal.R
+++ b/tools/update-reveal.R
@@ -175,3 +175,13 @@
 })
 
 gert::git_add(plugin_folders)
+
+
+# Re-apply IDS-local patches ----------------------------------------------
+
+## The vendored dist/reveal.js carries local modifications on top of upstream
+## (currently: '?' opens the help overlay on non-US keyboard layouts). They
+## live in tools/patch-revealjs.py as exact-match replacements; re-apply them
+## after the update above. The script fails loudly if upstream changed the
+## patched code, so nothing is lost silently.
+system2("python3", "tools/patch-revealjs.py")