diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 3e4fa83467..49c5569f3f 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,8 @@
+*   Raises `ActiveRecord::IrreversibleOrderError` when using `last` with an irreversible
+    order.
+
+    *Rafael Mendonça França*
+
 *   Raises when a through association has an ambiguous reflection name.
 
     *Rafael Mendonça França*
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 270511bede..dd92f40dee 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -152,14 +152,6 @@ module ActiveRecord
       result = result.reverse_order!
 
       limit ? result.reverse : result.first
-    rescue ActiveRecord::IrreversibleOrderError
-      ActiveSupport::Deprecation.warn(<<-WARNING.squish)
-          Finding a last element by loading the relation when SQL ORDER
-          can not be reversed is deprecated.
-          Rails 5.1 will raise ActiveRecord::IrreversibleOrderError in this case.
-          Please call `to_a.last` if you still want to load the relation.
-      WARNING
-      find_last(limit)
     end
 
     # Same as #last but raises ActiveRecord::RecordNotFound if no record
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index d6d24004fe..f1459ae125 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -592,7 +592,7 @@ class FinderTest < ActiveRecord::TestCase
   end
 
   def test_last_with_irreversible_order
-    assert_deprecated do
+    assert_raises(ActiveRecord::IrreversibleOrderError) do
       Topic.order("coalesce(author_name, title)").last
     end
   end