diff --git a/doc/16-upgrading-icinga-2.md b/doc/16-upgrading-icinga-2.md
index 08e66aed4..6eaec877d 100644
--- a/doc/16-upgrading-icinga-2.md
+++ b/doc/16-upgrading-icinga-2.md
@@ -289,6 +289,12 @@ It will also attempt to fix them, the following log entry is perfectly fine.
If you still encounter problems, please follow [this troubleshooting entry](15-troubleshooting.md#troubleshooting-api-missing-runtime-objects).
+### DB IDO MySQL Schema
+
+The schema for MySQL contains an optional update which
+drops unneeded indexes. You don't necessarily need to apply
+this update.
+
### Documentation
* `Custom attributes` have been renamed to `Custom variables` following the name `vars` and their usage in backends and web interfaces.