diff --git a/unleash-client.gemspec b/unleash-client.gemspec
index db38e0b..b4dc147 100644
--- a/unleash-client.gemspec
+++ b/unleash-client.gemspec
@@ -40,11 +40,9 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "simplecov", "~> 0.21.2"
   spec.add_development_dependency "simplecov-lcov", "~> 0.8.0"
 
-  # NOTE: only require rbs/steep in supported ruby versions. In EOL ruby/jruby, just ignore.
-  # rubocop:disable Gemspec/RubyVersionGlobalsUsage
-  if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('2.6') && RUBY_ENGINE != 'jruby'
-    spec.add_development_dependency "rbs", "~> 2.7"
-    spec.add_development_dependency "steep", "~> 1.2"
+  # NOTE: only require rbs/steep in MRI ruby versions. Ignore jruby.
+  unless RUBY_ENGINE == 'jruby'
+    spec.add_development_dependency "rbs", "~> 3.8.1"
+    spec.add_development_dependency "steep", "~> 1.9.3"
   end
-  # rubocop:enable Gemspec/RubyVersionGlobalsUsage
 end