diff --git a/examples/tests.modal b/examples/tests.modal
index 03a3027..fdb8b22 100644
--- a/examples/tests.modal
+++ b/examples/tests.modal
@@ -28,6 +28,12 @@ dup (abc) (abc abc) test
 swap (abc def) (def abc) test
 compare (abc abc abc) (#t) test
 
+?(?-) (Empty register replacement)
+
+<> (replace-empty ?x) (?y)
+
+replace-empty abc = ?y test
+
 ?(?-) (Lambdas)
 
 ?((?x) ((?x ?x) =)) abc (abc abc) test