diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fbab7e3..b61f341 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,9 +13,9 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: "3.12"
 
@@ -29,7 +29,7 @@ jobs:
     needs: test
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
         with:
           fetch-depth: 0
           token: ${{ secrets.GITHUB_TOKEN }}
diff --git a/Dockerfile b/Dockerfile
index 50c9375..8eaef38 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,6 +1,6 @@
 # Dockerfile
 
-FROM python:3.12-slim
+FROM python:3.12-slim@sha256:090ba77e2958f6af52a5341f788b50b032dd4ca28377d2893dcf1ecbdfdfe203
 
 WORKDIR /app