diff --git a/.gitignore b/.gitignore
index 1a386ea..8f526a8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -35,5 +35,6 @@ web/themes/contrib/
 web/update.php
 web/web.config
 
+# Docker.
 .env
 docker-compose.override.yaml
diff --git a/Dockerfile b/Dockerfile
index 500608d..556ce21 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -29,6 +29,8 @@ USER root
 RUN apt-get update -yqq \
   && apt-get install -yqq --no-install-recommends \
     git libpng-dev libjpeg-dev libzip-dev mariadb-client unzip
+  && rm -rf /var/lib/apt/lists/* /usr/share/doc /usr/share/man \
+  && apt-get clean
 
 RUN docker-php-ext-configure gd --with-jpeg