diff --git a/lib/active_hash/base.rb b/lib/active_hash/base.rb
index 043d140..464fa44 100644
--- a/lib/active_hash/base.rb
+++ b/lib/active_hash/base.rb
@@ -64,9 +64,7 @@ def field_names
       #  # => ["id", "name", "code"]
       #
       def column_names
-        field_names.map do |field|
-          field.respond_to?(:name) ? field.name : field.to_s.freeze
-        end
+        field_names.map(&:name)
       end
 
       def the_meta_class