diff --git a/gemfiles/oldest.gemfile b/gemfiles/oldest.gemfile
index fc99bc8..b2877e3 100644
--- a/gemfiles/oldest.gemfile
+++ b/gemfiles/oldest.gemfile
@@ -8,7 +8,7 @@ source 'https://rubygems.org'
 gemspec(path: Pathname(__dir__).parent)
 
 group :development, :test do
-  gem 'rake', '~> 13.0.6'
+  gem 'rake', '~> 13.2.1'
 end
 
 group :development do
@@ -21,7 +21,12 @@ group :development do
 end
 
 group :test do
-  gem 'rspec', '3.5.0'
+  gem 'rspec', '3.13.0'
+  # Required to drop ostruct for ruby 3.5 or later.
+  # See below commits
+  #   - https://github.com/rspec/rspec/commit/07a5612bf96427e24e50a6e975a71784d340dd2b
+  #   - https://github.com/rspec/rspec/commit/3fc400f466e30d1df19688df6164bf2b5937f570
+  gem 'rspec-core', '3.13.2'
   gem 'power_assert', '2.0.3'
   gem 'irb', '1.4.0'
   gem 'warning', '~> 1.3.0'