diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 0166336527..72d0484e54 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -29,16 +29,9 @@ jobs:
   make:
     strategy:
       matrix:
-        include:
-          - test_task: 'check'
-            os: 'macos-11'
-            configure: ''
-          - test_task: 'check'
-            os: 'macos-12'
-            configure: '--enable-shared'
-          - test_task: 'check'
-            os: 'macos-arm-oss'
-            configure: ''
+        test_task: ['check']
+        configure: ['']
+        os: ${{ fromJSON(format('["macos-11","macos-12"{0}]', (github.repository == 'ruby/ruby' && ',"macos-arm-oss"' || ''))) }}
       fail-fast: false
 
     env:
diff --git a/.github/workflows/yjit-macos.yml b/.github/workflows/yjit-macos.yml
index 469cc3db9e..71522f0a18 100644
--- a/.github/workflows/yjit-macos.yml
+++ b/.github/workflows/yjit-macos.yml
@@ -45,7 +45,8 @@ jobs:
     runs-on: macos-arm-oss
 
     if: >-
-      ${{!(false
+      ${{github.repository == 'ruby/ruby' &&
+      !(false
       || contains(github.event.head_commit.message, '[DOC]')
       || contains(github.event.pull_request.title, '[DOC]')
       || contains(github.event.pull_request.labels.*.name, 'Documentation')