diff --git a/lib/shoulda/matchers/active_record/validate_uniqueness_of_matcher.rb b/lib/shoulda/matchers/active_record/validate_uniqueness_of_matcher.rb
index 4ce092f0a..fe7466849 100644
--- a/lib/shoulda/matchers/active_record/validate_uniqueness_of_matcher.rb
+++ b/lib/shoulda/matchers/active_record/validate_uniqueness_of_matcher.rb
@@ -818,9 +818,7 @@ def next_value_for(scope, previous_value)
         end
 
         def next_scalar_value_for(scope, previous_value)
-          column = column_for(scope)
-
-          if column.type == :uuid
+          if uuid?(scope)
             SecureRandom.uuid
           elsif defined_as_enum?(scope)
             available_values = available_enum_values_for(scope, previous_value)
@@ -838,6 +836,13 @@ def next_scalar_value_for(scope, previous_value)
           end
         end
 
+        def uuid?(scope)
+          [
+            column_for(scope),
+            attribute_type_for(scope),
+          ].compact.map(&:type).include? :uuid
+        end
+
         def all_scopes_are_booleans?
           @options[:scopes].all? do |scope|
             @all_records.map(&scope).all? { |s| boolean_value?(s) }
@@ -931,6 +936,12 @@ def column_for(scope)
           model.columns_hash[scope.to_s]
         end
 
+        def attribute_type_for(scope)
+          if model.respond_to?(:attribute_types)
+            model.attribute_types[scope.to_s]
+          end
+        end
+
         def column_limit_for(attribute)
           column_for(attribute).try(:limit)
         end
diff --git a/spec/support/unit/helpers/active_model_versions.rb b/spec/support/unit/helpers/active_model_versions.rb
index db7037de7..9d4d48d8e 100644
--- a/spec/support/unit/helpers/active_model_versions.rb
+++ b/spec/support/unit/helpers/active_model_versions.rb
@@ -28,5 +28,9 @@ def active_model_supports_absence_validation?
     def active_model_supports_strict?
       active_model_version >= 3.2
     end
+
+    def active_model_supports_attributes_api?
+      ::ActiveModel::VERSION::MAJOR >= 5
+    end
   end
 end
diff --git a/spec/unit/shoulda/matchers/active_record/validate_uniqueness_of_matcher_spec.rb b/spec/unit/shoulda/matchers/active_record/validate_uniqueness_of_matcher_spec.rb
index c165b394c..2b5ebccf5 100644
--- a/spec/unit/shoulda/matchers/active_record/validate_uniqueness_of_matcher_spec.rb
+++ b/spec/unit/shoulda/matchers/active_record/validate_uniqueness_of_matcher_spec.rb
@@ -1475,6 +1475,49 @@ def name=(name)
     end
   end
 
+  if active_model_supports_attributes_api?
+    context 'Rails 5 attributes API' do
+      it 'builds uuid for attributes API type :uuid' do
+        scopes = {
+          scopes: [
+            {
+              name:        :uuid,
+              column_type: :string,
+              value_type:  :string,
+              options:     {
+                array: false,
+              },
+            },
+          ],
+        }
+        model = define_model_validating_uniqueness(scopes)
+
+        module ActiveRecord
+          module Type
+            class Uuid < ActiveRecord::Type::String
+              def type
+                :uuid
+              end
+            end
+          end
+        end
+
+        ActiveRecord::Type.register(:uuid,
+          ActiveRecord::Type::Uuid,
+          override: false,)
+        model.attribute(:uuid, :uuid)
+
+        record = model.new(uuid: next_scalar_value_for(:uuid, '', model.new))
+        expect(SecureRandom).to receive(:uuid).and_call_original
+
+        expect(record).to validate_uniqueness.
+          scoped_to(:uuid).
+          ignoring_case_sensitivity
+      end
+    end
+
+  end
+
   let(:model_attributes) { {} }
 
   def default_attribute
@@ -1560,6 +1603,12 @@ def dummy_scalar_value_for(attribute_type)
     end
   end
 
+  def next_scalar_value_for(scope, previous_value, record)
+    subject = validate_uniqueness
+    subject.instance_variable_set(:@given_record, record)
+    subject.send(:next_scalar_value_for, scope, previous_value)
+  end
+
   def next_version_of(value, value_type)
     if value.is_a?(Array)
       [ next_version_of(value[0], value_type) ]