diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 22ee2238cee2d18e2f493b29886986bea5db451b..1724ea95b013983233b77a4bdff5923f2a43222c 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -617,7 +617,7 @@ def association_primary_key(klass = nil)
       #   # => [:tag, :tags]
       #
       def source_reflection_names
-        (options[:source] ? [options[:source]] : [name.to_s.singularize, name]).uniq
+        options[:source] ? [options[:source]] : [name.to_s.singularize, name].uniq
       end
 
       def source_reflection_name # :nodoc: