diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 88546695e8838e5ae50e4e7d3b823df51df6bb29..b9782fcca0d39ba1da2d4cec072dd8d7d8572c0b 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   Remove `DEFAULT_CHARSET` and `DEFAULT_COLLATION` in `MySQLDatabaseTasks`.
+
+    We should omit the collation entirely rather than providing a default.
+    Then the choice is the responsibility of the server and MySQL distribution.
+
+    *Ryuta Kamizono*
+
 *   Alias `ActiveRecord::Relation#left_joins` to
     `ActiveRecord::Relation#left_outer_joins`.
 
diff --git a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
index 8929aa85c8f38242d16988b0c283797f7e774b29..100df9c6c60cd3c67f97bc19cc87d66a3147bd7f 100644
--- a/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
+++ b/activerecord/lib/active_record/tasks/mysql_database_tasks.rb
@@ -1,8 +1,6 @@
 module ActiveRecord
   module Tasks # :nodoc:
     class MySQLDatabaseTasks # :nodoc:
-      DEFAULT_CHARSET     = ENV['CHARSET']   || 'utf8'
-      DEFAULT_COLLATION   = ENV['COLLATION'] || 'utf8_unicode_ci'
       ACCESS_DENIED_ERROR = 1045
 
       delegate :connection, :establish_connection, to: ActiveRecord::Base
@@ -87,12 +85,6 @@ def creation_options
         Hash.new.tap do |options|
           options[:charset]     = configuration['encoding']   if configuration.include? 'encoding'
           options[:collation]   = configuration['collation']  if configuration.include? 'collation'
-
-          # Set default charset only when collation isn't set.
-          options[:charset]   ||= DEFAULT_CHARSET unless options[:collation]
-
-          # Set default collation only when charset is also default.
-          options[:collation] ||= DEFAULT_COLLATION if options[:charset] == DEFAULT_CHARSET
         end
       end
 
diff --git a/activerecord/test/cases/tasks/mysql_rake_test.rb b/activerecord/test/cases/tasks/mysql_rake_test.rb
index a93fa572577dcab66c03d1897c27e2c575d5d21e..5cbe7e30aad4cc52e05f674b01cb25ba6d71db63 100644
--- a/activerecord/test/cases/tasks/mysql_rake_test.rb
+++ b/activerecord/test/cases/tasks/mysql_rake_test.rb
@@ -21,28 +21,21 @@ def test_establishes_connection_without_database
       ActiveRecord::Tasks::DatabaseTasks.create @configuration
     end
 
-    def test_creates_database_with_default_encoding_and_collation
+    def test_creates_database_with_no_default_options
       @connection.expects(:create_database).
-        with('my-app-db', charset: 'utf8', collation: 'utf8_unicode_ci')
+        with('my-app-db', {})
 
       ActiveRecord::Tasks::DatabaseTasks.create @configuration
     end
 
-    def test_creates_database_with_given_encoding_and_default_collation
-      @connection.expects(:create_database).
-        with('my-app-db', charset: 'utf8', collation: 'utf8_unicode_ci')
-
-      ActiveRecord::Tasks::DatabaseTasks.create @configuration.merge('encoding' => 'utf8')
-    end
-
-    def test_creates_database_with_given_encoding_and_no_collation
+    def test_creates_database_with_given_encoding
       @connection.expects(:create_database).
         with('my-app-db', charset: 'latin1')
 
       ActiveRecord::Tasks::DatabaseTasks.create @configuration.merge('encoding' => 'latin1')
     end
 
-    def test_creates_database_with_given_collation_and_no_encoding
+    def test_creates_database_with_given_collation
       @connection.expects(:create_database).
         with('my-app-db', collation: 'latin1_swedish_ci')
 
@@ -203,9 +196,9 @@ def test_establishes_connection_to_the_appropriate_database
       ActiveRecord::Tasks::DatabaseTasks.purge @configuration
     end
 
-    def test_recreates_database_with_the_default_options
+    def test_recreates_database_with_no_default_options
       @connection.expects(:recreate_database).
-        with('test-db', charset: 'utf8', collation: 'utf8_unicode_ci')
+        with('test-db', {})
 
       ActiveRecord::Tasks::DatabaseTasks.purge @configuration
     end