diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index dff9d28..9462cd2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,15 +15,15 @@ jobs:
     runs-on: [ self-hosted, ubuntu-latest ]
 
     steps:
-    - uses: actions/checkout@v6
+    - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
 
     - name: Set up Python 3.11
-      uses: actions/setup-python@v6
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
       with:
         python-version: "3.11"
 
     - name: Cache pre-commit hooks
-      uses: actions/cache@v4
+      uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
       with:
         path: ~/.cache/pre-commit
         key: ${{ runner.os }}-precommit-${{ hashFiles('.pre-commit-config.yaml') }}