diff --git a/frontend/Dockerfile b/frontend/Dockerfile
index ef59e9b..99352f7 100644
--- a/frontend/Dockerfile
+++ b/frontend/Dockerfile
@@ -6,8 +6,8 @@ WORKDIR /app
 # Copy package files
 COPY package*.json ./
 
-# Install dependencies
-RUN npm install
+# Install dependencies — use ci for reproducible installs (exact lock file versions)
+RUN npm ci
 
 # Copy source code
 COPY . .
@@ -25,7 +25,7 @@ FROM node:20-alpine AS build
 WORKDIR /app
 
 COPY package*.json ./
-RUN npm install
+RUN npm ci
 
 COPY . .
 RUN npm run build