diff --git a/.github/workflows/flake.yml b/.github/workflows/flake.yml
index 77eef85..662152d 100644
--- a/.github/workflows/flake.yml
+++ b/.github/workflows/flake.yml
@@ -10,7 +10,7 @@ jobs:
   check-flake:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4.1.7
+    - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
     - uses: DeterminateSystems/flake-checker-action@v8
     - uses: DeterminateSystems/nix-installer-action@v12
     - uses: DeterminateSystems/magic-nix-cache-action@v7
@@ -31,7 +31,7 @@ jobs:
     name: ${{ matrix.name }}-build
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v4.1.7
+    - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
     - uses: DeterminateSystems/flake-checker-action@v8
     - uses: DeterminateSystems/nix-installer-action@v12
     - uses: DeterminateSystems/magic-nix-cache-action@v7