2 files changed, 14 insertions, 3 deletions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 10ecd068d3..419967b833 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1273,9 +1273,16 @@ module ActiveRecord
             if send(reflection.name).loaded? || reflection.options[:finder_sql]
               send(reflection.name).map(&:id)
             else
-              send(reflection.name).all(:select => "#{reflection.quoted_table_name}.#{reflection.klass.primary_key}").map(&:id)
+              if reflection.through_reflection && reflection.source_reflection.belongs_to?
+                through = reflection.through_reflection
+                primary_key = reflection.source_reflection.primary_key_name
+                send(through.name).all(:select => "DISTINCT #{through.quoted_table_name}.#{primary_key}").map!(&:"#{primary_key}")
+              else
+                send(reflection.name).all(:select => "#{reflection.quoted_table_name}.#{reflection.klass.primary_key}").map!(&:id)
+              end
             end
           end
+
         end
 
         def collection_accessor_methods(reflection, association_proxy_class, writer = true)
diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index 7a4712d7c8..8529ff0285 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -243,8 +243,12 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     assert_equal 2, people(:michael).jobs.size
   end
 
-  def test_get_ids
-    assert_equal [posts(:welcome).id, posts(:authorless).id].sort, people(:michael).post_ids.sort
+  def test_get_ids_for_belongs_to_source
+    assert_sql(/DISTINCT/) { assert_equal [posts(:welcome).id, posts(:authorless).id].sort, people(:michael).post_ids.sort }
+  end
+
+  def test_get_ids_for_has_many_source
+    assert_equal [comments(:eager_other_comment1).id], authors(:mary).comment_ids
   end
 
   def test_get_ids_for_loaded_associations