diff --git a/caddy2/php7.4-debian/Dockerfile b/caddy2/php7.4-debian/Dockerfile
index 55f661f..f480905 100644
--- a/caddy2/php7.4-debian/Dockerfile
+++ b/caddy2/php7.4-debian/Dockerfile
@@ -21,7 +21,7 @@ ENV PHP_EXTENSIONS \
 ENV PECL_EXTENSIONS \
     redis
 
-RUN apt-get install -y curl zip unzip libzip-dev
+RUN apt-get install -y curl zip unzip libzip-dev libpng-dev
 RUN pecl install $PECL_EXTENSIONS \
     && docker-php-ext-install -j "$(nproc)" $PHP_EXTENSIONS \
     && docker-php-ext-enable $PECL_EXTENSIONS \