diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index 7239270c4d..e234e02032 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -56,15 +56,7 @@ module ActiveRecord
     #
     #   Person.sum(:age) # => 4562
     def sum(*args)
-      if block_given?
-        ActiveSupport::Deprecation.warn(
-          "Calling #sum with a block is deprecated and will be removed in Rails 4.1. " \
-          "If you want to perform sum calculation over the array of elements, use `to_a.sum(&block)`."
-        )
-        self.to_a.sum(*args) {|*block_args| yield(*block_args)}
-      else
-        calculate(:sum, *args)
-      end
+      calculate(:sum, *args)
     end
 
     # This calculates aggregate values in the given column. Methods for count, sum, average,
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 058c812dca..9f64ecd845 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -1747,12 +1747,6 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_deprecated { klass.has_many :foo, :counter_sql => 'lol' }
   end
 
-  test "sum calculation with block for array compatibility is deprecated" do
-    assert_deprecated do
-      posts(:welcome).comments.sum { |c| c.id }
-    end
-  end
-
   test "has many associations on new records use null relations" do
     post = Post.new
 
diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index f49bef2346..095b78c6c8 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -410,12 +410,6 @@ class CalculationsTest < ActiveRecord::TestCase
         Account.where("credit_limit > 50").from('accounts').sum(:credit_limit)
   end
 
-  def test_sum_array_compatibility_deprecation
-    assert_deprecated do
-      assert_equal Account.sum(:credit_limit), Account.sum(&:credit_limit)
-    end
-  end
-
   def test_average_with_from_option
     assert_equal Account.average(:credit_limit), Account.from('accounts').average(:credit_limit)
     assert_equal Account.where("credit_limit > 50").average(:credit_limit),