diff --git a/lib/rb/thrift.gemspec b/lib/rb/thrift.gemspec
index bc436dc..99856e8 100644
--- a/lib/rb/thrift.gemspec
+++ b/lib/rb/thrift.gemspec
@@ -27,8 +27,8 @@
 
   s.require_paths = %w[lib ext]
 
-  s.add_development_dependency "rake"
-  s.add_development_dependency "rspec", "1.3.2"
-  s.add_development_dependency "mongrel"
+  s.add_development_dependency 'rake'
+  s.add_development_dependency 'rspec', '~> 2.11.0'
+  s.add_development_dependency 'mongrel', "1.2.0.pre2"
 end