diff --git a/mutant-rspec.gemspec b/mutant-rspec.gemspec
index 9d2558771..4d1ce0c95 100644
--- a/mutant-rspec.gemspec
+++ b/mutant-rspec.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |gem|
   gem.extra_rdoc_files = %w[LICENSE]
 
   gem.add_runtime_dependency('mutant', "~> #{gem.version}")
-  gem.add_runtime_dependency('rspec-core', '>= 3.4.0', '< 3.8.0')
+  gem.add_runtime_dependency('rspec-core', '>= 3.4.0', '< 4.0.0')
 
   gem.add_development_dependency('bundler', '~> 1.3', '>= 1.3.5')
 end