Patch #553277: Accept callbacks that are callable, not callbacks that are true.
diff --git a/Misc/ACKS b/Misc/ACKS
index b413540..1897e30 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -226,6 +226,7 @@
 Ben Jackson
 Paul Jackson
 David Jacobs
+Geert Jansen
 Jack Jansen
 Bill Janssen
 Drew Jenkins