diff --git a/activesupport/lib/active_support/inflections.rb b/activesupport/lib/active_support/inflections.rb
index 527cce2594..e91289e18f 100644
--- a/activesupport/lib/active_support/inflections.rb
+++ b/activesupport/lib/active_support/inflections.rb
@@ -23,10 +23,11 @@ module ActiveSupport
     inflect.plural(/(quiz)$/i, '\1zes')
 
     inflect.singular(/s$/i, '')
+    inflect.singular(/(ss)$/i, '\1')
     inflect.singular(/(n)ews$/i, '\1ews')
     inflect.singular(/([ti])a$/i, '\1um')
-    inflect.singular(/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)ses$/i, '\1\2sis')
-    inflect.singular(/(^analy)ses$/i, '\1sis')
+    inflect.singular(/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)(sis|ses)$/i, '\1\2sis')
+    inflect.singular(/(^analy)(sis|ses)$/i, '\1sis')
     inflect.singular(/([^f])ves$/i, '\1fe')
     inflect.singular(/(hive)s$/i, '\1')
     inflect.singular(/(tive)s$/i, '\1')
@@ -36,12 +37,12 @@ module ActiveSupport
     inflect.singular(/(m)ovies$/i, '\1ovie')
     inflect.singular(/(x|ch|ss|sh)es$/i, '\1')
     inflect.singular(/(m|l)ice$/i, '\1ouse')
-    inflect.singular(/(bus)es$/i, '\1')
+    inflect.singular(/(bus)(es)?$/i, '\1')
     inflect.singular(/(o)es$/i, '\1')
     inflect.singular(/(shoe)s$/i, '\1')
-    inflect.singular(/(cris|ax|test)es$/i, '\1is')
-    inflect.singular(/(octop|vir)i$/i, '\1us')
-    inflect.singular(/(alias|status)es$/i, '\1')
+    inflect.singular(/(cris|ax|test)(is|es)$/i, '\1is')
+    inflect.singular(/(octop|vir)(us|i)$/i, '\1us')
+    inflect.singular(/(alias|status)(es)?$/i, '\1')
     inflect.singular(/^(ox)en/i, '\1')
     inflect.singular(/(vert|ind)ices$/i, '\1ex')
     inflect.singular(/(matr)ices$/i, '\1ix')
diff --git a/activesupport/test/inflector_test.rb b/activesupport/test/inflector_test.rb
index 3311d58254..5e62b289ff 100644
--- a/activesupport/test/inflector_test.rb
+++ b/activesupport/test/inflector_test.rb
@@ -65,6 +65,14 @@ class InflectorTest < ActiveSupport::TestCase
       assert_equal(plural.capitalize, ActiveSupport::Inflector.pluralize(plural.capitalize))
     end
   end
+  
+  SingularToPlural.each do |singular, plural|
+    define_method "test_singularize_singular_#{singular}" do
+      assert_equal(singular, ActiveSupport::Inflector.singularize(singular))
+      assert_equal(singular.capitalize, ActiveSupport::Inflector.singularize(singular.capitalize))
+    end
+  end
+  
 
   def test_overwrite_previous_inflectors
     assert_equal("series", ActiveSupport::Inflector.singularize("series"))