diff --git a/Makefile b/Makefile
index 560c62d..8576732 100644
--- a/Makefile
+++ b/Makefile
@@ -193,14 +193,11 @@ pseudoxml:
 
 install: vendor
 
-composer.phar:
-	docker/install-composer.sh
-
-vendor: composer.phar
-	php composer.phar install
+vendor:
+	composer install
 
 cs: install
-	./vendor/bin/phpcs -p --standard=PSR2 --ignore=vendor,_build .
+	./vendor/bin/phpcs .
 
 test: install
 	./vendor/bin/phpunit
diff --git a/docker/install-composer.sh b/docker/install-composer.sh
deleted file mode 100755
index d39d20a..0000000
--- a/docker/install-composer.sh
+++ /dev/null
@@ -1,17 +0,0 @@
-#!/bin/sh
-
-EXPECTED_SIGNATURE="$(wget -q -O - https://composer.github.io/installer.sig)"
-php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
-ACTUAL_SIGNATURE="$(php -r "echo hash_file('SHA384', 'composer-setup.php');")"
-
-if [ "$EXPECTED_SIGNATURE" != "$ACTUAL_SIGNATURE" ]
-then
-    >&2 echo 'ERROR: Invalid installer signature'
-    rm composer-setup.php
-    exit 1
-fi
-
-php composer-setup.php --quiet
-RESULT=$?
-rm composer-setup.php
-exit $RESULT