diff --git a/.github/workflows/zjit-macos.yml b/.github/workflows/zjit-macos.yml
index 53732103ec44d6..8f2ca884b16ef8 100644
--- a/.github/workflows/zjit-macos.yml
+++ b/.github/workflows/zjit-macos.yml
@@ -36,6 +36,7 @@ jobs:
             configure: '--enable-zjit=dev'
             run_opts: '--zjit-call-threshold=1'
             specopts: '-T --zjit-call-threshold=1'
+            test_all_opts: '--seed=46450'
 
           - test_task: 'zjit-check' # zjit-test + quick feedback of test_zjit.rb
             configure: '--enable-yjit=dev --enable-zjit'
@@ -117,9 +118,15 @@ jobs:
           TEST_BUNDLED_GEMS_ALLOW_FAILURES: ''
           SYNTAX_SUGGEST_TIMEOUT: '5'
           PRECHECK_BUNDLED_GEMS: 'no'
-          TESTS: ${{ matrix.tests }}
+          TESTS: ${{ matrix.test_all_opts }}
         continue-on-error: ${{ matrix.continue-on-test_task || false }}
 
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.test_task }} ${{ matrix.configure }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
   result:
     if: ${{ always() }}
     name: ${{ github.workflow }} result
diff --git a/.github/workflows/zjit-ubuntu.yml b/.github/workflows/zjit-ubuntu.yml
index 76b5b2c48948a8..3dfa8260a80fc1 100644
--- a/.github/workflows/zjit-ubuntu.yml
+++ b/.github/workflows/zjit-ubuntu.yml
@@ -55,6 +55,7 @@ jobs:
             configure: '--enable-zjit=dev'
             run_opts: '--zjit-call-threshold=1'
             specopts: '-T --zjit-call-threshold=1'
+            test_all_opts: '--seed=39471'
 
           - test_task: 'zjit-check' # zjit-test + quick feedback of test_zjit.rb
             configure: '--enable-yjit --enable-zjit=dev'
@@ -159,9 +160,15 @@ jobs:
           SYNTAX_SUGGEST_TIMEOUT: '5'
           ZJIT_BINDGEN_DIFF_OPTS: '--exit-code'
           LIBCLANG_PATH: ${{ matrix.libclang_path }}
-          TESTS: ${{ matrix.tests }}
+          TESTS: ${{ matrix.test_all_opts }}
         continue-on-error: ${{ matrix.continue-on-test_task || false }}
 
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.test_task }} ${{ matrix.configure }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
   result:
     if: ${{ always() }}
     name: ${{ github.workflow }} result
diff --git a/test/ruby/test_zjit.rb b/test/ruby/test_zjit.rb
index 1d80093d57d47a..5f59f9fc02b240 100644
--- a/test/ruby/test_zjit.rb
+++ b/test/ruby/test_zjit.rb
@@ -487,7 +487,6 @@ def test
   end
 
   def test_invokebuiltin
-    omit 'Test fails at the moment due to not handling optional parameters'
     assert_compiles '["."]', %q{
       def test = Dir.glob(".")
       test