diff --git a/README.md b/README.md
index f296fa2..1383738 100644
--- a/README.md
+++ b/README.md
@@ -9,6 +9,9 @@
 * Another private repo contains stuff in a more
   approachable format, f.e. for dealing with
   updating sealed-secrets: `gitops-tbrnt-private`
+* `_tests` contains some Open Policy Agent rego
+  files which are used in the Drone CI pipeline
+  to validate configuration.
 
 ## Usage