diff --git a/activerecord/lib/active_record/validations.rb b/activerecord/lib/active_record/validations.rb
index 53942d34f7..4d1c92330b 100755
--- a/activerecord/lib/active_record/validations.rb
+++ b/activerecord/lib/active_record/validations.rb
@@ -254,7 +254,7 @@ module ActiveRecord
       # Configuration options:
       # * <tt>in</tt> - An enumerable object of available items
       # * <tt>message</tt> - Specifieds a customer error message (default is: "is not included in the list")
-      # * <tt>allows_nil</tt> - If set to true, skips this validation if the attribute is null (default is: false)
+      # * <tt>allow_nil</tt> - If set to true, skips this validation if the attribute is null (default is: false)
       def validates_inclusion_of(*attr_names)
         configuration = { :message => ActiveRecord::Errors.default_error_messages[:inclusion], :on => :save }
         configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)