diff --git a/docker-gitlabci/Dockerfile b/docker-gitlabci/Dockerfile
index 5fd7f880..8472933f 100644
--- a/docker-gitlabci/Dockerfile
+++ b/docker-gitlabci/Dockerfile
@@ -28,7 +28,7 @@ RUN apt-get update && apt-get install -y \
   npm \
   # Code coverage for unit test \
   php-pear php-dev \
-  && apt purge php8.3-redis \
+  && apt purge php8.3-redis && apt autoremove --purge \
   && rm -rf /var/lib/apt/lists/*
 
 # Install needed NPM packages and download chrome for the domjudge user
@@ -37,8 +37,9 @@ RUN su domjudge -c "cd /home/domjudge && \
                     npx puppeteer browsers install chrome && \
                     npm cache clean --force"
 
-# Install needed global PHP modules
-RUN composer -n require justinrainbow/json-schema phpcompatibility/php-compatibility:dev-develop
+# Install needed global PHP modules, squizlabs/php_codesniffer is soft requirement for phpcompatibility/php-compatibility
+RUN composer -n require justinrainbow/json-schema phpcompatibility/php-compatibility:dev-develop squizlabs/php_codesniffer
+RUN composer config --no-plugins allow-plugins.dealerdirect/phpcodesniffer-composer-installer true
 
 # Install other PHP versions
 RUN add-apt-repository ppa:ondrej/php -y && apt-get update && \