Reflections are now strings, so we will need to call to_s on the mapping name

Author: Kyle d'Oliveira

lib/polymorphic_integer_type/extensions.rb

@@ -9,7 +9,7 @@ def belongs_to(name, scope = nil, options = {})
         super
         if options[:polymorphic] && integer_type
           mapping = PolymorphicIntegerType::Mapping[name]
-          foreign_type = reflections[name].foreign_type
+          foreign_type = reflections[name.to_s].foreign_type
           self._polymorphic_foreign_types << foreign_type
 
           define_method foreign_type do