diff --git a/Gemfile b/Gemfile
old mode 100755
new mode 100644
index 8b52476..d15ef73
--- a/Gemfile
+++ b/Gemfile
@@ -32,7 +32,7 @@ gem 'mail'
 
 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