diff --git a/lib/shoulda/matchers/active_record/have_db_index_matcher.rb b/lib/shoulda/matchers/active_record/have_db_index_matcher.rb
index f244b028..5a7cc4ff 100644
--- a/lib/shoulda/matchers/active_record/have_db_index_matcher.rb
+++ b/lib/shoulda/matchers/active_record/have_db_index_matcher.rb
@@ -98,11 +98,7 @@ module Shoulda # :nodoc:
         end
 
         def normalize_columns_to_array(columns)
-          if columns.class == Array
-            columns.map(&:to_s)
-          else
-            [columns.to_s]
-          end
+          Array.wrap(columns).map(&:to_s)
         end
       end
     end