diff --git a/runtime/indent/README.txt b/runtime/indent/README.txt
index a424b4f..8b11436 100644
--- a/runtime/indent/README.txt
+++ b/runtime/indent/README.txt
@@ -43,3 +43,5 @@
 The user may have several options set unlike you, try to write the file such
 that it works with any option settings.  Also be aware of certain features not
 being compiled in.
+
+To test the indent file, see testdir/README.txt.