1 files changed, 8 insertions, 3 deletions
diff --git a/lib/arel/relations/writes/update.rb b/lib/arel/relations/writes/update.rb
index 2e90de3a52..52ca6ecf05 100644
--- a/lib/arel/relations/writes/update.rb
+++ b/lib/arel/relations/writes/update.rb
@@ -10,9 +10,7 @@ module Arel
     def to_sql(formatter = nil)
       [
         "UPDATE #{table_sql} SET",
-        assignments.collect do |attribute, value|
-          "#{engine.quote_column_name(attribute.name)} = #{attribute.format(value)}"
-        end.join(",\n"),
+        map_assignments,
         ("WHERE #{wheres.map(&:to_sql).join('\n\tAND ')}"  unless wheres.blank?  ),
         ("LIMIT #{taken}"                                      unless taken.blank?    )
       ].join("\n")
@@ -21,5 +19,12 @@ module Arel
     def call(connection = engine)
       connection.update(to_sql)
     end
+
+    def map_assignments
+      assignments.collect do |attribute, value|
+        attribute.respond_to?(:name) ?
+          "#{engine.quote_column_name(attribute.name)} = #{attribute.format(value)}" : attribute
+      end.join(",\n")
+    end
   end
 end