diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index b5db0693fefbff399885eec9eb4c7ad073addd2c..af70a81414de3d3df2b298d7540fa7b3c46e5dfe 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   `#singularize` and `#pluralize` now respect uncountables for the specified locale.
+
+    *Eilis Hamilton*
+
 *   Add ActiveSupport::CurrentAttributes to provide a thread-isolated attributes singleton.
     Primary use case is keeping all the per-request attributes easily available to the whole system.
     
diff --git a/activesupport/lib/active_support/inflector/methods.rb b/activesupport/lib/active_support/inflector/methods.rb
index 1b089a75384867f33c9eabafdbc7ae888e268031..ff1a0cb8c71e76e05e8124ac7b57d3494a999433 100644
--- a/activesupport/lib/active_support/inflector/methods.rb
+++ b/activesupport/lib/active_support/inflector/methods.rb
@@ -28,7 +28,7 @@ module Inflector
     #   pluralize('CamelOctopus')     # => "CamelOctopi"
     #   pluralize('ley', :es)         # => "leyes"
     def pluralize(word, locale = :en)
-      apply_inflections(word, inflections(locale).plurals)
+      apply_inflections(word, inflections(locale).plurals, locale)
     end
 
     # The reverse of #pluralize, returns the singular form of a word in a
@@ -45,7 +45,7 @@ def pluralize(word, locale = :en)
     #   singularize('CamelOctopi')      # => "CamelOctopus"
     #   singularize('leyes', :es)       # => "ley"
     def singularize(word, locale = :en)
-      apply_inflections(word, inflections(locale).singulars)
+      apply_inflections(word, inflections(locale).singulars, locale)
     end
 
     # Converts strings to UpperCamelCase.
@@ -387,12 +387,15 @@ def const_regexp(camel_cased_word)
 
       # Applies inflection rules for +singularize+ and +pluralize+.
       #
-      #  apply_inflections('post', inflections.plurals)    # => "posts"
-      #  apply_inflections('posts', inflections.singulars) # => "post"
-      def apply_inflections(word, rules)
+      # If passed an optional +locale+ parameter, the uncountables will be
+      # found for that locale.
+      #
+      #  apply_inflections('post', inflections.plurals, :en)    # => "posts"
+      #  apply_inflections('posts', inflections.singulars, :en) # => "post"
+      def apply_inflections(word, rules, locale = :en)
         result = word.to_s.dup
 
-        if word.empty? || inflections.uncountables.uncountable?(result)
+        if word.empty? || inflections(locale).uncountables.uncountable?(result)
           result
         else
           rules.each { |(rule, replacement)| break if result.sub!(rule, replacement) }
diff --git a/activesupport/test/inflector_test.rb b/activesupport/test/inflector_test.rb
index 14bc10513be485c18782a0eb796bef3fecda508a..ef956eda9014e72fbffc59635c2c2fa0f5f2ae3b 100644
--- a/activesupport/test/inflector_test.rb
+++ b/activesupport/test/inflector_test.rb
@@ -420,6 +420,8 @@ def test_inflector_locality
       inflect.singular(/es$/, "")
 
       inflect.irregular("el", "los")
+
+      inflect.uncountable("agua")
     end
 
     assert_equal("hijos", "hijo".pluralize(:es))
@@ -432,12 +434,17 @@ def test_inflector_locality
     assert_equal("los", "el".pluralize(:es))
     assert_equal("els", "el".pluralize)
 
+    assert_equal("agua", "agua".pluralize(:es))
+    assert_equal("aguas", "agua".pluralize)
+
     ActiveSupport::Inflector.inflections(:es) { |inflect| inflect.clear }
 
     assert ActiveSupport::Inflector.inflections(:es).plurals.empty?
     assert ActiveSupport::Inflector.inflections(:es).singulars.empty?
+    assert ActiveSupport::Inflector.inflections(:es).uncountables.empty?
     assert !ActiveSupport::Inflector.inflections.plurals.empty?
     assert !ActiveSupport::Inflector.inflections.singulars.empty?
+    assert !ActiveSupport::Inflector.inflections.uncountables.empty?
   end
 
   def test_clear_all