diff --git a/README.md b/README.md
index cbaf1cc8d..f86b7c373 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,10 @@ This action currently supports these versions of MRI, JRuby and TruffleRuby:
 
 `ruby-debug` is the same as `ruby-head` but with assertions enabled (`-DRUBY_DEBUG=1`).
 
+`ruby-asan` is the same as `ruby-head` but with AddressSanitizer (ASan) enabled, helpful for finding memory issues in native extensions.
+Native extensions are automatically compiled with AddressSanitizer when using `ruby-asan`.
+`ruby-asan` is currently only available on `ubuntu-24.04`.
+
 Regarding Windows ruby master builds, `mingw` is a MSYS2/MinGW build, `head` & `ucrt` are MSYS2/UCRT64
 builds, and `mswin` is a MSVC/VS 2022 build.