diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 83264200..55104d68 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -39,7 +39,7 @@ cache:
     - vendor
 
 lint rubocop code:
-  image: "ruby:3.2"
+  image: "ruby:3.3"
   variables:
     BUNDLE_WITHOUT: test:coverage:assorted
   before_script:
@@ -47,7 +47,7 @@ lint rubocop code:
   script:
     - bundle exec rake rubocop
 lint rubocop wiki:
-  image: "ruby:3.2"
+  image: "ruby:3.3"
   rules:
     - if: $CI_PIPELINE_SOURCE == "schedule"
   variables:
@@ -61,7 +61,7 @@ lint rubocop wiki:
         - rubocop-md
 
       AllCops:
-        TargetRubyVersion: 3.2
+        TargetRubyVersion: 3.3
         DisabledByDefault: true
       FILE
   script:
@@ -93,13 +93,18 @@ test ruby 3/2:
   <<: *yjit_matrix
   script:
     ./spec.sh ruby 3.2
+test ruby 3/3:
+  <<: *test_settings
+  <<: *yjit_matrix
+  script:
+    ./spec.sh ruby 3.3
 test truffleruby:
   <<: *test_settings
   script:
     ./spec.sh truffleruby latest
   allow_failure: true
 regression tests:
-  image: "ruby:3.2"
+  image: "ruby:3.3"
   variables:
     BUNDLE_WITHOUT: lint:assorted
     CI: 1
@@ -120,7 +125,7 @@ coverage:
   variables:
     BUNDLE_WITHOUT: lint:test:assorted
 
-  image: "ruby:3.2"
+  image: "ruby:3.3"
   script:
     - gem install simplecov --no-doc
     # this is a workaround, because simplecov doesn't support relative paths.
@@ -142,7 +147,7 @@ pages:
   stage: deploy
   needs:
     - coverage
-  image: "ruby:3.2"
+  image: "ruby:3.3"
   before_script:
     - gem install hanna-nouveau
   script:
diff --git a/README.md b/README.md
index e757f2aa..f8e4cd58 100644
--- a/README.md
+++ b/README.md
@@ -136,7 +136,7 @@ The test suite runs against [httpbin proxied over nghttp2](https://nghttp2.org/h
 
 All Rubies greater or equal to 2.7, and always latest JRuby and Truffleruby.
 
-**Note**: This gem is tested against all latest patch versions, i.e. if you're using 3.2.0 and you experience some issue, please test it against 3.2.$latest before creating an issue.
+**Note**: This gem is tested against all latest patch versions, i.e. if you're using 3.3.0 and you experience some issue, please test it against 3.3.$latest before creating an issue.
 
 ## Resources
 |               |                                                        |
diff --git a/docker-compose-ruby-3.3.yml b/docker-compose-ruby-3.3.yml
new file mode 100644
index 00000000..5f4cdb92
--- /dev/null
+++ b/docker-compose-ruby-3.3.yml
@@ -0,0 +1,27 @@
+version: '3'
+services:
+  httpx:
+    image: ruby:3.3
+    environment:
+      - HTTPBIN_COALESCING_HOST=another
+      - HTTPX_RESOLVER_URI=https://doh/dns-query
+    links:
+      - "nghttp2:another"
+    depends_on:
+      - doh
+
+  doh:
+    image: registry.gitlab.com/os85/httpx/nghttp2:1
+    depends_on:
+      - doh-proxy
+    entrypoint:
+      /usr/local/bin/nghttpx
+    volumes:
+      - ./test/support/ci:/home
+    command:
+      --conf /home/doh-nghttp.conf --no-ocsp --frontend '*,443'
+
+  doh-proxy:
+    image: publicarray/doh-proxy
+    environment:
+      - "UNBOUND_SERVICE_HOST=127.0.0.11"
diff --git a/test/support/ci/build.sh b/test/support/ci/build.sh
index 8407c499..69d47a78 100755
--- a/test/support/ci/build.sh
+++ b/test/support/ci/build.sh
@@ -82,7 +82,7 @@ if [[ "$RUBY_ENGINE" = "ruby" ]]; then
   COVERAGE_KEY="$RUBY_ENGINE-$RUBY_VERSION-integration-tests" bundle exec rake integration_tests
 fi
 
-if [[ ${RUBY_VERSION:0:3} = "3.2" ]] && [[ "$RUBY_ENGINE" = "ruby" ]]; then
+if [[ ${RUBY_VERSION:0:3} = "3.3" ]] && [[ "$RUBY_ENGINE" = "ruby" ]]; then
   # regression tests
   # Testing them only with main ruby
   # COVERAGE_KEY="$RUBY_ENGINE-$RUBY_VERSION-regression-tests" bundle exec rake regression_tests