diff --git a/Source/Dockerfile b/Source/Dockerfile
index 34f2a78..432d46f 100644
--- a/Source/Dockerfile
+++ b/Source/Dockerfile
@@ -3,7 +3,7 @@ RUN apt-get update && apt-get install -y git zip
 COPY . /var/www/html
 WORKDIR /var/www/html/Config
 RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
-RUN composer update && composer install
+RUN composer update --prefer-source ../. && composer install --prefer-source ../.
 WORKDIR /var/www/html
 RUN Config/vendor/bin/phpunit .\Tests --coverage-clover coverage.xml