diff --git a/.github/actions/setup/directories/action.yml b/.github/actions/setup/directories/action.yml
index ea5f2720ef343e..2878fa09331c1c 100644
--- a/.github/actions/setup/directories/action.yml
+++ b/.github/actions/setup/directories/action.yml
@@ -29,6 +29,13 @@ inputs:
     description: >-
       If set to true, additionally runs `make up`.
 
+  dummy-files:
+    required: false
+    type: boolean
+    default: ''
+    description: >-
+      If set to true, creates dummy files in build dir.
+
 outputs: {} # nothing?
 
 runs:
@@ -110,3 +117,12 @@ runs:
         sudo chmod -R go-w /usr/share
         chmod -v go-w $HOME $HOME/.config || :
         sudo bash -c 'IFS=:; for d in '"$PATH"'; do chmod -v go-w $d; done' || :
+
+    - if: inputs.dummy-files == 'true'
+      shell: bash
+      working-directory: ${{ inputs.builddir }}
+      run: |
+        : Create dummy files in build dir
+        for basename in {a..z} {A..Z} {0..9} foo bar test zzz; do
+          echo > ${basename}.rb "raise %(do not load ${basename}.rb)"
+        done
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index ca5e5d9aa794bd..e235941503afcf 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -69,6 +69,7 @@ jobs:
           srcdir: src
           builddir: build
           makeup: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
 
       - name: Run configure
         run: ../src/configure -C --disable-install-doc ${{ matrix.configure }}
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 0548e1b420cb40..2709b0d9494b3d 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -78,6 +78,7 @@ jobs:
           srcdir: src
           builddir: build
           makeup: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
 
       - name: Run configure
         env:
@@ -92,11 +93,6 @@ jobs:
 
       - run: $SETARCH make
 
-      - name: Create dummy files in build dir
-        run: |
-          $SETARCH ./miniruby -e '(("a".."z").to_a+("A".."Z").to_a+("0".."9").to_a+%w[foo bar test zzz]).each{|basename|File.write("#{basename}.rb", "raise %(do not load #{basename}.rb)")}'
-        if: ${{ matrix.test_task == 'check' }}
-
       - name: make ${{ matrix.test_task }}
         run: >-
           $SETARCH make -s ${{ matrix.test_task }}
diff --git a/.github/workflows/yjit-ubuntu.yml b/.github/workflows/yjit-ubuntu.yml
index 4a3d4dc61a9f2e..7567a45089af01 100644
--- a/.github/workflows/yjit-ubuntu.yml
+++ b/.github/workflows/yjit-ubuntu.yml
@@ -130,6 +130,7 @@ jobs:
           srcdir: src
           builddir: build
           makeup: true
+          dummy-files: ${{ matrix.test_task == 'check' }}
 
       - name: Install Rust
         if: ${{ matrix.rust_version }}
@@ -145,11 +146,6 @@ jobs:
 
       - run: make
 
-      - name: Create dummy files in build dir
-        run: |
-          ./miniruby -e '(("a".."z").to_a+("A".."Z").to_a+("0".."9").to_a+%w[foo bar test zzz]).each{|basename|File.write("#{basename}.rb", "raise %(do not load #{basename}.rb)")}'
-        if: ${{ matrix.test_task == 'check' }}
-
       - name: Enable YJIT through ENV
         run: echo "RUBY_YJIT_ENABLE=1" >> $GITHUB_ENV