diff --git a/CHANGELOG b/CHANGELOG
index ad9afbf..2e6e986 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,6 @@
+[2008-11-13]
+  - allow uppercase meridian to be valid
+
 [2008-10-28]
   - fixed bug when dirty attributes not reflecting change when attribute changed from time value to nil [reported by Brad (pvjq)]
   - fixes for Rails 2.2 compatibility. Will refactor in to Rails version specific branches in the future.
diff --git a/lib/validates_timeliness/formats.rb b/lib/validates_timeliness/formats.rb
index 8ebd655..457f084 100644
--- a/lib/validates_timeliness/formats.rb
+++ b/lib/validates_timeliness/formats.rb
@@ -123,7 +123,7 @@ module ValidatesTimeliness
       { 'ss'   => [ /s{2,}/, '(\d{2})',   :sec ] },
       { 's'    => [ /s{1}/,  '(\d{1,2})', :sec ] },
       { 'u'    => [ /u{1,}/, '(\d{1,6})', :usec ] },
-      { 'ampm' => [ /ampm/,  '((?:a|p)\.?m\.?)', :meridian ] },
+      { 'ampm' => [ /ampm/,  '((?:[aApP])\.?[mM]\.?)', :meridian ] },
       { 'zo'   => [ /zo/,    '(?:[+-]\d{2}:?\d{2})'] },
       { 'tz'   => [ /tz/,    '(?:[A-Z]{1,4})' ] }, 
       { '_'    => [ /_/,     '\s?' ] }
diff --git a/spec/formats_spec.rb b/spec/formats_spec.rb
index e176ad6..d3b691d 100644
--- a/spec/formats_spec.rb
+++ b/spec/formats_spec.rb
@@ -13,11 +13,11 @@ describe ValidatesTimeliness::Formats do
     end
     
     it "should generate regexp for time with meridian" do
-      generate_regexp_str('hh:nn:ss ampm').should == '/(\d{2}):(\d{2}):(\d{2}) ((?:a|p)\.?m\.?)/'
+      generate_regexp_str('hh:nn:ss ampm').should == '/(\d{2}):(\d{2}):(\d{2}) ((?:[aApP])\.?[mM]\.?)/'
     end
     
     it "should generate regexp for time with meridian and optional space between" do
-      generate_regexp_str('hh:nn:ss_ampm').should == '/(\d{2}):(\d{2}):(\d{2})\s?((?:a|p)\.?m\.?)/'
+      generate_regexp_str('hh:nn:ss_ampm').should == '/(\d{2}):(\d{2}):(\d{2})\s?((?:[aApP])\.?[mM]\.?)/'
     end
     
     it "should generate regexp for time with single or double digits" do
@@ -83,13 +83,13 @@ describe ValidatesTimeliness::Formats do
         'h.nn'      => {:pass => ['2.12', '12.12'], :fail => ['2.1', '12:12']},
         'h nn'      => {:pass => ['2 12', '12 12'], :fail => ['2 1', '2.12', '12:12']},
         'h-nn'      => {:pass => ['2-12', '12-12'], :fail => ['2-1', '2.12', '12:12']},
-        'h:nn_ampm' => {:pass => ['2:12am', '2:12 pm'], :fail => ['1:2am', '1:12  pm', '2.12am']},
+        'h:nn_ampm' => {:pass => ['2:12am', '2:12 pm', '2:12 AM', '2:12PM'], :fail => ['1:2am', '1:12  pm', '2.12am']},
         'h.nn_ampm' => {:pass => ['2.12am', '2.12 pm'], :fail => ['1:2am', '1:12  pm', '2:12am']},
         'h nn_ampm' => {:pass => ['2 12am', '2 12 pm'], :fail => ['1 2am', '1 12  pm', '2:12am']},
         'h-nn_ampm' => {:pass => ['2-12am', '2-12 pm'], :fail => ['1-2am', '1-12  pm', '2:12am']},
         'h_ampm'    => {:pass => ['2am', '2 am', '12 pm'], :fail => ['1.am', '12  pm', '2:12am']},
-      }    
-      format_tests.each do |format, values|      
+      }
+      format_tests.each do |format, values|
         it "should correctly validate times in format '#{format}'" do
           regexp = generate_regexp(format)
           values[:pass].each {|value| value.should match(regexp)}