diff --git a/example/example-callbacks.ref b/example/example-callbacks.ref
index 72f751a..c6f8f53 100644
--- a/example/example-callbacks.ref
+++ b/example/example-callbacks.ref
@@ -30,6 +30,7 @@
 Move constructions: True
 argument matches dummy_function
 eval(1) = 2
+roundtrip (got None)..
 roundtrip..
 argument matches dummy_function
 eval(1) = 2