diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index 1b9a30f1b7..8d3a3c2bd0 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* TZInfo caches Timezone instances in its own internal hash cache, so TimeZone::MAPPING doesn't need to cache them as well [Geoff Buesing]
+
 * Adding TimeZone#parse [Geoff Buesing]
 
 * Adding TimeZone#at and DateTime#to_f [Geoff Buesing]
diff --git a/activesupport/lib/active_support/values/time_zone.rb b/activesupport/lib/active_support/values/time_zone.rb
index 1d33dcbf32..085fab9731 100644
--- a/activesupport/lib/active_support/values/time_zone.rb
+++ b/activesupport/lib/active_support/values/time_zone.rb
@@ -247,13 +247,7 @@ class TimeZone
     end
     
     def tzinfo
-      return @tzinfo if @tzinfo
-      @tzinfo = MAPPING[name]
-      if String === @tzinfo
-        @tzinfo = TZInfo::Timezone.get(@tzinfo)
-        MAPPING[name] = @tzinfo
-      end
-      @tzinfo
+      @tzinfo ||= TZInfo::Timezone.get(MAPPING[name])
     end
     
   rescue LoadError # Tzinfo gem is not available