3 files changed, 16 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/dynamic_matchers.rb b/activerecord/lib/active_record/dynamic_matchers.rb
index e650ebcf64..5caab09038 100644
--- a/activerecord/lib/active_record/dynamic_matchers.rb
+++ b/activerecord/lib/active_record/dynamic_matchers.rb
@@ -84,13 +84,18 @@ module ActiveRecord
         "#{finder}(#{attributes_hash})"
       end
 
+      # The parameters in the signature may have reserved Ruby words, in order
+      # to prevent errors, we start each param name with `_`.
+      #
       # Extended in activerecord-deprecated_finders
       def signature
-        attribute_names.join(', ')
+        attribute_names.map { |name| "_#{name}" }.join(', ')
       end
 
+      # Given that the parameters starts with `_`, the finder needs to use the
+      # same parameter name.
       def attributes_hash
-        "{" + attribute_names.map { |name| ":#{name} => #{name}" }.join(',') + "}"
+        "{" + attribute_names.map { |name| ":#{name} => _#{name}" }.join(',') + "}"
       end
 
       def finder
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index 5e8f1c851f..7a00f7fa8f 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -12,6 +12,7 @@ require 'models/developer'
 require 'models/customer'
 require 'models/toy'
 require 'models/matey'
+require 'models/dog'
 
 class FinderTest < ActiveRecord::TestCase
   fixtures :companies, :topics, :entrants, :developers, :developers_projects, :posts, :comments, :accounts, :authors, :customers, :categories, :categorizations
@@ -641,6 +642,13 @@ class FinderTest < ActiveRecord::TestCase
     assert_raise(ActiveRecord::RecordNotFound) { Topic.find_by_title!("The First Topic!") }
   end
 
+  def test_find_by_on_attribute_that_is_a_reserved_word
+    dog_alias = 'Dog'
+    dog = Dog.create(alias: dog_alias)
+
+    assert_equal dog, Dog.find_by_alias(dog_alias)
+  end
+
   def test_find_by_one_attribute_that_is_an_alias
     assert_equal topics(:first), Topic.find_by_heading("The First Topic")
     assert_nil Topic.find_by_heading("The First Topic!")
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index 92e2e4d409..ac546fc296 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -245,6 +245,7 @@ ActiveRecord::Schema.define do
     t.integer :trainer_id
     t.integer :breeder_id
     t.integer :dog_lover_id
+    t.string  :alias
   end
 
   create_table :edges, force: true, id: false do |t|