diff --git a/.github/workflows/pr-build.yml b/.github/workflows/pr-build.yml
index 88d2c70df..2d5daca47 100644
--- a/.github/workflows/pr-build.yml
+++ b/.github/workflows/pr-build.yml
@@ -22,9 +22,10 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: '20'
+          cache: 'npm'
 
       - name: Install dependencies
-        run: npm install
+        run: npm ci
 
       - name: Lint MDX heading hierarchy
         run: npm run lint:mdx
diff --git a/docker/Dockerfile b/docker/Dockerfile
index ac7cc4a03..0deb1ea31 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -10,8 +10,8 @@ RUN npm install --global pm2
 # Utilise Docker cache to save re-installing dependencies if unchanged
 COPY ./package*.json ./
 
-# Install dependencies
-RUN npm install --production
+# Install dependencies (npm ci = clean, reproducible install from the lockfile)
+RUN npm ci --omit=dev
 
 # Copy all files
 COPY ./ ./