--- /dev/null
+use strict;
+use warnings;
+use Test::More tests => 1;
+
+eval {
+ package Request;
+ use Mouse::Util::TypeConstraints;
+
+ type 'Int' => where { 1};
+};
+like $@, qr/The type constraint 'Int' has already been created in Mouse::Util::TypeConstraints and cannot be created again in Request/;