diff --git a/README.md b/README.md
index 9aa64c6..1be7fba 100644
--- a/README.md
+++ b/README.md
@@ -101,6 +101,7 @@ inViewport(true); // showDialog marked as dirty but does not recompute its store
 shouldShow(true); // showDialog is already marked as dirty. Nothing else happens.
 showDialog(); // showDialog recomputes its stored result and unsets the dirty flag.
 
+// adding a subscription will change showDialog's internal behavior
 showDialog.subscribe(console.log.bind(console));
 
 inViewport(false); // showDialog result recomputed and `false` is written to the console.