1 files changed, 2 insertions, 4 deletions
diff --git a/lib/arel/nodes/string_join.rb b/lib/arel/nodes/string_join.rb
index ea7912f92b..7fb0033c0f 100644
--- a/lib/arel/nodes/string_join.rb
+++ b/lib/arel/nodes/string_join.rb
@@ -1,10 +1,8 @@
 module Arel
   module Nodes
     class StringJoin < Arel::Nodes::Join
-      undef :constraint
-
-      def initialize left, right
-        super(left, right, nil)
+      def initialize left, right = nil
+        super
       end
     end
   end