diff --git a/.github/workflows/stable.yml b/.github/workflows/stable.yml
index 891a4b7f..6e128b11 100644
--- a/.github/workflows/stable.yml
+++ b/.github/workflows/stable.yml
@@ -19,6 +19,7 @@ jobs:
           - '3.2'
           - '3.3'
           - jruby-9.4
+          - truffleruby
 
     steps:
       - uses: actions/checkout@v4
@@ -28,5 +29,13 @@ jobs:
           ruby-version: ${{ matrix.ruby-version }}
           bundler-cache: true
 
-      - run: |
-          bundle exec rake
+      - name: Run tests
+        run: bundle exec rake
+        if: matrix.ruby-version != 'truffleruby'
+
+      # Run only `rake spec` on truffleruby, because just `rake` runs `rubocop spec cucumber`.
+      # There is no value to rerun rubocop here.
+      # cucumber fails because it uses an old childprocess which depends on fork.
+      - name: Run specs (truffleruby)
+        run: bundle exec rake spec
+        if: matrix.ruby-version == 'truffleruby'
diff --git a/.github/workflows/unstable.yml b/.github/workflows/unstable.yml
index 70d676a0..037384c8 100644
--- a/.github/workflows/unstable.yml
+++ b/.github/workflows/unstable.yml
@@ -17,6 +17,7 @@ jobs:
         ruby-version:
           - ruby-head
           - jruby-head
+          - truffleruby-head
 
     steps:
       - uses: actions/checkout@v4
@@ -25,8 +26,14 @@ jobs:
         with:
           ruby-version: ${{ matrix.ruby-version }}
           bundler-cache: true
-        continue-on-error: ${{ (matrix.ruby-version == 'ruby-head') || (matrix.ruby-version == 'jruby-head') }}
 
-      - run: |
-          bundle exec rake
-        continue-on-error: ${{ (matrix.ruby-version == 'ruby-head') || (matrix.ruby-version == 'jruby-head') }}
+      - name: Run tests
+        run: bundle exec rake
+        if: matrix.ruby-version != 'truffleruby-head'
+
+      # Run only `rake spec` on truffleruby, because just `rake` runs `rubocop spec cucumber`.
+      # There is no value to rerun rubocop here.
+      # cucumber fails because it uses an old childprocess which depends on fork.
+      - name: Run specs (truffleruby)
+        run: bundle exec rake spec
+        if: matrix.ruby-version == 'truffleruby-head'
diff --git a/spec/return_codes_spec.rb b/spec/return_codes_spec.rb
index 36b2dd31..527388f1 100644
--- a/spec/return_codes_spec.rb
+++ b/spec/return_codes_spec.rb
@@ -34,6 +34,8 @@
         end
 
         it "prints a message to STDERR" do
+          # https://github.com/oracle/truffleruby/issues/3535
+          skip "fails on truffleruby" if RUBY_ENGINE == "truffleruby" && command.include?("testunit_bad.rb")
           expect(@stderr).to match(/stopped.+SimpleCov.+previous.+error/i)
         end
       end