diff --git a/activerecord/lib/active_record/nested_attributes.rb b/activerecord/lib/active_record/nested_attributes.rb
index 70a460d..3f657a4 100644
--- a/activerecord/lib/active_record/nested_attributes.rb
+++ b/activerecord/lib/active_record/nested_attributes.rb
@@ -354,7 +354,7 @@ module ActiveRecord
         association.to_a
       else
         attribute_ids = attributes_collection.map {|a| a['id'] || a[:id] }.compact
-        attribute_ids.present? ? association.all(:conditions => {:id => attribute_ids}) : []
+        attribute_ids.present? ? association.all(:conditions => {association.primary_key => attribute_ids}) : []
       end
 
       attributes_collection.each do |attributes|
diff --git a/activerecord/test/cases/nested_attributes_test.rb b/activerecord/test/cases/nested_attributes_test.rb
index eae8ae7..e9fffd4 100644
--- a/activerecord/test/cases/nested_attributes_test.rb
+++ b/activerecord/test/cases/nested_attributes_test.rb
@@ -6,6 +6,8 @@ require "models/parrot"
 require "models/treasure"
 require "models/man"
 require "models/interest"
+require "models/owner"
+require "models/pet"
 require 'active_support/hash_with_indifferent_access'
 
 module AssertRaiseWithMessage
@@ -707,3 +709,22 @@ class TestNestedAttributesLimit < ActiveRecord::TestCase
     end
   end
 end
+
+class TestNestedAttributesWithNonStandardPrimaryKeys < ActiveRecord::TestCase
+  fixtures :owners, :pets
+  def setup
+    Owner.accepts_nested_attributes_for :pets
+    @owner = owners(:ashley)
+    @pet1, @pet2 = pets(:chew), pets(:mochi)
+    @params = {
+      :pets_attributes => {
+	'0' => { :id => @pet1.id, :name => 'Foo' },
+	'1' => { :id => @pet2.id, :name => 'Bar' }
+      }
+    }
+  end
+  def test_should_update_existing_records_with_non_standard_primary_key
+    @owner.update_attributes(@params)
+    assert_equal ['Foo', 'Bar'], @owner.pets.map(&:name)
+  end
+end