diff --git a/lib/validates_timeliness/instance_tag.rb b/lib/validates_timeliness/instance_tag.rb
index 9c97bad..e20427a 100644
--- a/lib/validates_timeliness/instance_tag.rb
+++ b/lib/validates_timeliness/instance_tag.rb
@@ -23,7 +23,7 @@ module ValidatesTimeliness
       
       raw_value = value_before_type_cast(object)
       
-      if raw_value.acts_like?(:time) || raw_value.is_a?(Date)
+      if raw_value.nil? || raw_value.acts_like?(:time) || raw_value.is_a?(Date)
         return value_without_timeliness(object)
       end
       
diff --git a/spec/instance_tag_spec.rb b/spec/instance_tag_spec.rb
index cddd336..409b24b 100644
--- a/spec/instance_tag_spec.rb
+++ b/spec/instance_tag_spec.rb
@@ -6,9 +6,9 @@ describe ValidatesTimeliness::InstanceTag, :type => :helper do
     @person = Person.new
   end
   
-  it "should display invalid date as date_select values" do
-    @person.birth_date_and_time = "2008-02-30 12:00:00"
-    output = date_select(:person, :birth_date_and_time, :include_blank => true)
+  it "should display invalid datetime as datetime_select values" do
+    @person.birth_date_and_time = "2008-02-30 12:00:22"
+    output = datetime_select(:person, :birth_date_and_time, :include_blank => true, :include_seconds => true)
    
     output.should have_tag('select[id=person_birth_date_and_time_1i]') do
       with_tag('option[selected=selected]', '2008')
@@ -19,5 +19,20 @@ describe ValidatesTimeliness::InstanceTag, :type => :helper do
     output.should have_tag('select[id=person_birth_date_and_time_3i]') do
       with_tag('option[selected=selected]', '30')
     end
+    output.should have_tag('select[id=person_birth_date_and_time_4i]') do
+      with_tag('option[selected=selected]', '12')
+    end
+    output.should have_tag('select[id=person_birth_date_and_time_5i]') do
+      with_tag('option[selected=selected]', '00')
+    end
+    output.should have_tag('select[id=person_birth_date_and_time_6i]') do
+      with_tag('option[selected=selected]', '22')
+    end
+  end
+  
+  it "should display datetime_select when datetime value is nil" do
+    @person.birth_date_and_time = nil
+    output = datetime_select(:person, :birth_date_and_time, :include_blank => true, :include_seconds => true)
+    output.should have_tag('select', 6)
   end
 end