diff --git a/lib/shallow_attributes/class_methods.rb b/lib/shallow_attributes/class_methods.rb
index 1353c66..71333a2 100644
--- a/lib/shallow_attributes/class_methods.rb
+++ b/lib/shallow_attributes/class_methods.rb
@@ -14,6 +14,14 @@ module ClassMethods
     #
     def inherited(subclass)
       super
+      if respond_to?(:descriptions)
+        subclass.descriptions.merge!(descriptions)
+      end
+
+      if respond_to?(:formats)
+        subclass.formats.merge!(formats)
+      end
+
       if respond_to?(:default_values)
         subclass.default_values.merge!(default_values)
       end
@@ -41,6 +49,14 @@ def mandatory_attributes
       @mandatory_attributes ||= {}
     end
 
+    def descriptions
+      @descriptions ||= {}
+    end
+
+    def formats
+      @formats ||= {}
+    end
+
     # Returns all class attributes.
     #
     # @example Create new User instance
@@ -88,6 +104,8 @@ def attribute(name, type, options = {})
 
       default_values[name] = options.delete(:default)
       mandatory_attributes[name] = options.delete(:present)
+      descriptions[name] = options.delete(:desc)
+      formats[name] = options.delete(:format)
 
       initialize_setter(name, type, options)
       initialize_getter(name)
diff --git a/lib/shallow_attributes/type.rb b/lib/shallow_attributes/type.rb
index ef66fc1..b99b380 100644
--- a/lib/shallow_attributes/type.rb
+++ b/lib/shallow_attributes/type.rb
@@ -7,6 +7,13 @@
 require 'shallow_attributes/type/time'
 require 'shallow_attributes/type/date'
 
+# Boolean class for working with bool values
+#
+# @private
+#
+# @since 0.9.4
+class Boolean; end
+
 module ShallowAttributes
   # Namespace for standard type classes
   #
@@ -30,7 +37,8 @@ class InvalidValueError < TypeError
       ::Integer  => ShallowAttributes::Type::Integer.new,
       ::String   => ShallowAttributes::Type::String.new,
       ::Time     => ShallowAttributes::Type::Time.new,
-      ::Date     => ShallowAttributes::Type::Date.new
+      ::Date     => ShallowAttributes::Type::Date.new,
+      ::Boolean     => ShallowAttributes::Type::Boolean.new
     }.freeze
 
     class << self
@@ -56,7 +64,10 @@ class << self
       #
       # @since 0.1.0
       def coerce(type, value, options = {})
-        type_instance(type).coerce(value, options)
+        instance = type_instance(type, value)
+        return instance.coerce(instance.attributes, options) if instance.respond_to? :attributes
+
+        instance.coerce(value, options)
       end
 
     private
@@ -78,8 +89,14 @@ def coerce(type, value, options = {})
       # @return [Class]
       #
       # @since 0.1.0
-      def type_instance(klass)
-        DEFAULT_TYPE_OBJECTS[klass] || ShallowAttributes::Type.const_get(klass.name).new
+      def type_instance(klass, value = {})
+        return DEFAULT_TYPE_OBJECTS[klass] if DEFAULT_TYPE_OBJECTS[klass]
+
+        instantiable = ShallowAttributes::Type.const_get(klass.name)
+
+        return instantiable.new(value) if instantiable < ShallowAttributes
+
+        instantiable.new
       end
     end
   end
diff --git a/test/custom_types_test.rb b/test/custom_types_test.rb
index b0955bf..a3473bf 100644
--- a/test/custom_types_test.rb
+++ b/test/custom_types_test.rb
@@ -152,5 +152,28 @@ class Person
         end
       end
     end
+    describe 'when custom type receives parameters not considered as attributes' do
+      let(:person) do
+        Person.new(
+            name: 'John',
+            address: {
+                street: 'Street',
+                number: '12'
+            }
+        )
+      end
+
+      it 'ignores the non existence parameter' do
+        hash = person.attributes
+        hash.must_equal({
+            name: 'John',
+            addresses: [],
+            address: {
+                street: 'Street',
+                zipcode: '111111'
+            }
+        })
+      end
+    end
   end
 end