diff --git a/oga.gemspec b/oga.gemspec
index 118bbf5..0afafac 100644
--- a/oga.gemspec
+++ b/oga.gemspec
@@ -37,7 +37,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'ast'
 
   s.add_development_dependency 'rake'
-  s.add_development_dependency 'rspec'
+  s.add_development_dependency 'rspec', ['~> 3.0']
   s.add_development_dependency 'yard'
   s.add_development_dependency 'simplecov'
   s.add_development_dependency 'kramdown'
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 8413653..1449041 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -11,4 +11,12 @@ require_relative 'support/parsing'
 RSpec.configure do |config|
   config.color = true
   config.include Oga::ParsingHelpers
+
+  config.expect_with :rspec do |c|
+    c.syntax = [:should, :expect]
+  end
+
+  config.mock_with :rspec do |c|
+    c.syntax = [:should, :expect]
+  end
 end