diff --git a/Dockerfile b/Dockerfile
index 863d517..ca29f90 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -54,7 +54,7 @@ RUN set -ex \
  && ln -sf /dev/stderr /var/log/nginx/error.log \
  && curl -s https://getcomposer.org/installer | php \
  && mv composer.phar /usr/local/bin/composer \
- && composer selfupdate 2.2.12
+ && composer selfupdate 2.2.18
 
 COPY root /