diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 3fa426b02..a544a70b0 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -23,7 +23,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.repo.full_name || github.repository }}
-          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.ref || github.ref }}
+          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.sha || github.sha }}
       - name: Run ShellCheck
         uses: ludeeus/action-shellcheck@1.1.0
         env:
@@ -36,7 +36,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.repo.full_name || github.repository }}
-          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.ref || github.ref }}
+          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.sha || github.sha }}
       - name: Install additional packages
         run: |
           set -ex
@@ -54,7 +54,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.repo.full_name || github.repository }}
-          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.ref || github.ref }}
+          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.sha || github.sha }}
       - name: Install additional packages
         run: |
           set -ex
@@ -77,7 +77,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.repo.full_name || github.repository }}
-          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.ref || github.ref }}
+          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.sha || github.sha }}
       - name: Install additional packages
         run: |
           set -ex
@@ -97,7 +97,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.repo.full_name || github.repository }}
-          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.ref || github.ref }}
+          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.sha || github.sha }}
       - name: Install additional packages
         run: |
           set -ex
@@ -130,7 +130,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.repo.full_name || github.repository }}
-          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.ref || github.ref }}
+          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.sha || github.sha }}
           fetch-depth: 0
           submodules: true
       - name: Build Docker image
@@ -169,7 +169,7 @@ jobs:
         uses: actions/checkout@v2
         with:
           repository: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.repo.full_name || github.repository }}
-          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.ref || github.ref }}
+          ref: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.sha || github.sha }}
           fetch-depth: 0
           submodules: true
       - name: Test Lua command-line interface