diff --git a/lib/disposable/twin/coercion.rb b/lib/disposable/twin/coercion.rb
index b360962..f850d77 100644
--- a/lib/disposable/twin/coercion.rb
+++ b/lib/disposable/twin/coercion.rb
@@ -25,7 +25,7 @@ def coercing_setter!(name, type, nilify=false)
 
       mod = Module.new do
         define_method("#{name}=") do |value|
-          super type.(value)
+          super type.(value) { value }
         end
       end
       include mod