diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 85587aa..f7a4cae 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,10 +9,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest, macos-latest ]
-        # TODO: Wait for supporting Ruby 3.0 in simplecov-cobertura.
-        # See https://github.com/dashingrocket/simplecov-cobertura/pull/16
-        # ruby: [ 2.5, 2.6, 2.7, 3.0 ]
-        ruby: [ 2.5, 2.6, 2.7 ]
+        ruby: [ 2.5, 2.6, 2.7, '3.0', 3.1, 3.2, 3.3 ]
     runs-on: ${{ matrix.os }}
 
     steps:
diff --git a/pb-serializer.gemspec b/pb-serializer.gemspec
index 5054d61..c8ad177 100644
--- a/pb-serializer.gemspec
+++ b/pb-serializer.gemspec
@@ -38,6 +38,6 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rspec", "~> 3.0"
   spec.add_development_dependency "rubocop", "0.67.2" # for onkcop
   spec.add_development_dependency "sqlite3", "~> 1.4"
-  spec.add_development_dependency "simplecov", "~> 0.18.5"
-  spec.add_development_dependency "simplecov-cobertura", "~> 1.3"
+  spec.add_development_dependency "simplecov", "~> 0.21.2"
+  spec.add_development_dependency "simplecov-cobertura", "~> 2.1"
 end