diff --git a/xray-rails.gemspec b/xray-rails.gemspec
index b4a0339..f392b08 100644
--- a/xray-rails.gemspec
+++ b/xray-rails.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |gem|
 
   gem.add_dependency 'rails', '>= 3.1.0'
 
-  gem.add_development_dependency 'rspec-rails'
+  gem.add_development_dependency 'rspec-rails', '~> 3.8'
 
   # Required for the dummy Rails app in spec/dummy
   gem.add_development_dependency 'sqlite3'