diff --git a/README.md b/README.md
index 8eb2b98..b6eec47 100644
--- a/README.md
+++ b/README.md
@@ -228,6 +228,9 @@ These operations are:
 - `lte`: tests if the flag value is less than or equal to the compared value.
 - `has`: tests if the flag value contains the compared value.
 - `nothave`: tests if the flag value does not contain the compared value.
+- `regex`: tests if the flag value matches the compared value regular expression.
+
+When defining regular expressions in YAML it is generally easier to wrap them in single quotes, for example `'^[abc]$`, to avoid issues with string escaping.
 
 # Roadmap
 Going forward we plan to release updates to kube-bench to add support for new releases of the Benchmark, which in turn we can anticipate being made for each new Kubernetes release.