diff --git a/rubycas-client-rails.gemspec b/rubycas-client-rails.gemspec
index 4953a10..260cd65 100644
--- a/rubycas-client-rails.gemspec
+++ b/rubycas-client-rails.gemspec
@@ -14,5 +14,5 @@ Gem::Specification.new do |s|
   s.rubyforge_project = %q{rubycas-client}
 
   s.add_dependency('rails', '>= 3.0.0')
-  s.add_dependency('rubycas-client', '>= 2.3.5')
+  s.add_dependency('rubycas-client', '~> 2.3.9.rc1')
 end