diff --git a/weaver.rb b/weaver.rb
index 00c993e..ae3e5b8 100644
--- a/weaver.rb
+++ b/weaver.rb
@@ -10,5 +10,6 @@ def weave events
     link m.events, :next_state
     link m.events.reverse, :previous_state
   end
+  nil
 end