diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 15eae7e..d9b071c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,10 +10,10 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
 
       - name: Set up Go
-        uses: actions/setup-go@v6
+        uses: actions/setup-go@924ae3a1cded613372ab5595356fb5720e22ba16 # v6.5.0
         with:
           go-version-file: 'go.mod'
           cache: true
@@ -34,7 +34,7 @@ jobs:
 
       - name: Set up mise (Go + Bun)
         if: always()
-        uses: jdx/mise-action@v4
+        uses: jdx/mise-action@e6a8b3978addb5a52f2b4cd9d91eafa7f0ab959d # v4.2.0
         with:
           install: true
 
diff --git a/.github/workflows/pinact.yml b/.github/workflows/pinact.yml
new file mode 100644
index 0000000..e72aac5
--- /dev/null
+++ b/.github/workflows/pinact.yml
@@ -0,0 +1,37 @@
+name: pinact
+
+on:
+  pull_request:
+    paths:
+      - '.github/workflows/**'
+      - '**/action.yml'
+      - '**/action.yaml'
+
+permissions:
+  contents: write
+
+concurrency:
+  group: pinact-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  pinact:
+    if: github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-latest
+    steps:
+      - name: Generate GitHub App token
+        id: app-token
+        uses: actions/create-github-app-token@29824e69f54612133e76f7eaac726eef6c875baf # v2.2.1
+        with:
+          app-id: ${{ secrets.APP_ID }}
+          private-key: ${{ secrets.SECRET_KEY }}
+
+      - name: Checkout
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+        with:
+          persist-credentials: false
+
+      - name: Pin actions
+        uses: suzuki-shunsuke/pinact-action@896d595f299e71d65b9d28349d6956abe144390a # v3.0.0
+        with:
+          github_token: ${{ steps.app-token.outputs.token }}
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 0dae0ab..fdc7357 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -17,13 +17,13 @@ jobs:
   goreleaser:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           fetch-depth: 0
           ref: ${{ github.event.release.tag_name || github.event.inputs.tag || github.ref }}
 
       - name: Set up Go
-        uses: actions/setup-go@v6
+        uses: actions/setup-go@924ae3a1cded613372ab5595356fb5720e22ba16 # v6.5.0
         with:
           go-version-file: 'go.mod'
           cache: true
@@ -34,7 +34,7 @@ jobs:
           app-id: ${{ secrets.APP_ID }}
           private-key: ${{ secrets.SECRET_KEY }}
       - name: Run GoReleaser
-        uses: goreleaser/goreleaser-action@v6
+        uses: goreleaser/goreleaser-action@e435ccd777264be153ace6237001ef4d979d3a7a # v6.4.0
         with:
           distribution: goreleaser
           version: latest
diff --git a/.github/workflows/tagpr.yml b/.github/workflows/tagpr.yml
index 59814bd..08e16f2 100644
--- a/.github/workflows/tagpr.yml
+++ b/.github/workflows/tagpr.yml
@@ -28,7 +28,7 @@ jobs:
         with:
           app-id: ${{ secrets.APP_ID }}
           private-key: ${{ secrets.SECRET_KEY }}
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           fetch-depth: 0
           ref: main
@@ -71,6 +71,6 @@ jobs:
           done
           echo "::error::commit->PR index not propagated after ~60s; failing to avoid a duplicate release PR. Re-run the workflow once GitHub recovers."
           exit 1
-      - uses: Songmu/tagpr@v1
+      - uses: Songmu/tagpr@e84001bd5dac8defa0c75b3913937d284a3b3660 # v1.20.0
         env:
           GITHUB_TOKEN: ${{ steps.app-token.outputs.token }}