diff --git a/Gemfile b/Gemfile
index 1840121..7fe5359 100644
--- a/Gemfile
+++ b/Gemfile
@@ -45,7 +45,7 @@ gem 'jbuilder', '~> 1.2'
 
 group :doc do
   # bundle exec rake doc:rails generates the API under doc/api.
-  gem 'sdoc', require: false
+  gem 'sdoc', '>= 1.0.0', require: false
 end
 
 # Use ActiveModel has_secure_password