diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index ec9f498c40..608d072e48 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -12,10 +12,9 @@ def initialize(options)
 
       def validate_each(record, attribute, value)
         finder_class = find_finder_class_for(record)
-        table = finder_class.arel_table
         value = map_enum_attribute(finder_class, attribute, value)
 
-        relation = build_relation(finder_class, table, attribute, value)
+        relation = build_relation(finder_class, attribute, value)
         if record.persisted?
           if finder_class.primary_key
             relation = relation.where.not(finder_class.primary_key => record.id_was || record.id)
@@ -23,7 +22,7 @@ def validate_each(record, attribute, value)
             raise UnknownPrimaryKey.new(finder_class, "Can not validate uniqueness for persisted record without primary key.")
           end
         end
-        relation = scope_relation(record, table, relation)
+        relation = scope_relation(record, relation)
         relation = relation.merge(options[:conditions]) if options[:conditions]
 
         if relation.exists?
@@ -50,7 +49,7 @@ def find_finder_class_for(record) #:nodoc:
         class_hierarchy.detect { |klass| !klass.abstract_class? }
       end
 
-      def build_relation(klass, table, attribute, value) #:nodoc:
+      def build_relation(klass, attribute, value) # :nodoc:
         if reflection = klass._reflect_on_association(attribute)
           attribute = reflection.foreign_key
           value = value.attributes[reflection.klass.primary_key] unless value.nil?
@@ -63,6 +62,7 @@ def build_relation(klass, table, attribute, value) #:nodoc:
 
         attribute_name = attribute.to_s
 
+        table = klass.arel_table
         column = klass.columns_hash[attribute_name]
         cast_type = klass.type_for_attribute(attribute_name)
 
@@ -80,7 +80,7 @@ def build_relation(klass, table, attribute, value) #:nodoc:
         end
       end
 
-      def scope_relation(record, table, relation)
+      def scope_relation(record, relation)
         Array(options[:scope]).each do |scope_item|
           if reflection = record.class._reflect_on_association(scope_item)
             scope_value = record.send(reflection.foreign_key)