diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 76aee452ca72286c5d938c2d28825640bdb80542..f4f52e85e320b93620bfbb91a5b7582f67e95e22 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -634,7 +634,7 @@ def change_column_default(table_name, column_name, default) #:nodoc:
         change_column table_name, column_name, column.sql_type, :default => default
       end
 
-      def change_column_null(table_name, column_name, null, default = nil)
+      def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
         column = column_for(table_name, column_name)
 
         unless null || default.nil?
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 70fc1a6bd8c7912034316a89838a54bed1284cd2..2a229ebf42979a7f96b8dd720ac741b5fb3144e8 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -438,7 +438,7 @@ def change_column_default(table_name, column_name, default) # :nodoc:
           end
         end
 
-        def change_column_null(table_name, column_name, null, default = nil)
+        def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
           clear_cache!
           unless null || default.nil?
             column = column_for(table_name, column_name)
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
index 7e184dd510cfa64524094454c46e98536c9d3958..31867695103c0d403393b73e57d790eda91afb2b 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb
@@ -450,7 +450,7 @@ def change_column_default(table_name, column_name, default) #:nodoc:
         end
       end
 
-      def change_column_null(table_name, column_name, null, default = nil)
+      def change_column_null(table_name, column_name, null, default = nil) #:nodoc:
         unless null || default.nil?
           exec_query("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
         end