diff --git a/lib/customer_fwd.rb b/lib/customer_fwd.rb
index 4a6f4350ed7df0ed3af030cf91423b7386245f21..fbf33631b8d7f2b697d988215b8609d22a5450e0 100644
--- a/lib/customer_fwd.rb
+++ b/lib/customer_fwd.rb
@@ -40,7 +40,7 @@ class CustomerFwd
 	end
 
 	value_semantics do
-		uri Either(String, NilClass)
+		uri Either(/:/, NilClass)
 		def_attr :timeout, Timeout, coerce: Timeout.method(:new)
 	end