diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
index bde2f6a..b50028b 100644
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -8,6 +8,8 @@ jobs:
   backend:
     name: Backend tests (Maven)
     runs-on: ['ubuntu-latest']
+    container:
+      image: maven:3.9-jdk-21
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -17,12 +19,6 @@ jobs:
           echo "Runner name: ${{ runner.name }}"
           echo "Runner labels: ${{ toJSON(runner.labels) }}"
 
-      - name: Set up JDK 21
-        uses: actions/setup-java@v4
-        with:
-          distribution: temurin
-          java-version: '21'
-
       - name: Cache Maven
         uses: actions/cache@v4
         with:
@@ -38,6 +34,8 @@ jobs:
   frontend:
     name: Frontend build (node)
     runs-on: ['ubuntu-latest']
+    container:
+      image: node:18-bullseye
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -64,4 +62,4 @@ jobs:
         run: |
           cd frontend
           npm ci
-          npm run build
+          npm run build
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