diff --git a/lib/customer_repo.rb b/lib/customer_repo.rb
index ef373804717cf68f769ace53bcfb5e67ff089c74..db19a27690e303ad0402bed3f973ded744a8158b 100644
--- a/lib/customer_repo.rb
+++ b/lib/customer_repo.rb
@@ -11,7 +11,7 @@ class CustomerRepo
 	class NotFound < RuntimeError; end
 
 	value_semantics do
-		set_user          Proc,       default: ->(**) {}
+		set_user          Proc,       default: ->(**) {}, coerce: :to_proc.to_proc
 		redis             Anything(), default: LazyObject.new { REDIS }
 		db                Anything(), default: LazyObject.new { DB }
 		braintree         Anything(), default: LazyObject.new { BRAINTREE }