diff --git a/Makefile b/Makefile
index 108f6912d6..8584274dec 100644
--- a/Makefile
+++ b/Makefile
@@ -89,7 +89,7 @@ docs:                       SUBDIRS=    doc
 install-docs:               SUBDIRS=    doc
 maintainer-conf:            SUBDIRS=                                 webapp
 maintainer-install:         SUBDIRS=                                 webapp
-inplace-install:            SUBDIRS=    doc               misc-tools webapp
+inplace-install:            SUBDIRS=    doc               misc-tools
 inplace-uninstall:          SUBDIRS=    doc               misc-tools
 dist:                       SUBDIRS=        lib sql       misc-tools
 clean:                      SUBDIRS=etc doc lib sql judge misc-tools webapp
@@ -227,6 +227,8 @@ inplace-install-l:
 # because judgehost-create-dirs sets wrong permissions:
 	$(MKDIR_P) $(domserver_tmpdir)
 	chmod a+rwx $(domserver_tmpdir)
+# Make sure we're running from a clean state:
+	(cd webapp && composer auto-scripts)
 	@echo ""
 	@echo "========== Maintainer Install Completed =========="
 	@echo ""
diff --git a/webapp/.gitignore b/webapp/.gitignore
index a3afa9e59b..70a4c6b3b2 100644
--- a/webapp/.gitignore
+++ b/webapp/.gitignore
@@ -8,7 +8,6 @@
 /var/log/*
 !var/log/.gitkeep
 /vendor/
-!vendor/Makefile
 
 ###> phpunit/phpunit ###
 /phpunit.xml
diff --git a/webapp/Makefile b/webapp/Makefile
index 0c4cbefe36..35db26d9f0 100644
--- a/webapp/Makefile
+++ b/webapp/Makefile
@@ -7,9 +7,34 @@ REC_TARGETS = domserver
 include $(TOPDIR)/Makefile.global
 
 # Subdirectories to recurse into for REC_TARGETS
-SUBDIRS = config vendor
+SUBDIRS = config
 
-maintainer-conf: .env.local
+domserver: composer-dump-autoload
+
+# Install PHP dependencies
+composer-dependencies:
+ifeq (, $(shell command -v composer 2> /dev/null))
+	$(error "'composer' command not found in $(PATH), install it via your package manager or https://getcomposer.org/download/")
+endif
+# We use --no-scripts here because at this point the autoload.php file is
+# not generated yet, which is needed to run the post-install scripts.
+	composer $(subst 1,-q,$(QUIET)) install --prefer-dist -o -a --no-scripts --no-plugins
+
+composer-dependencies-dev:
+	composer $(subst 1,-q,$(QUIET)) install --prefer-dist --no-scripts --no-plugins
+
+# Dump autoload dependencies (including plugins)
+# This is needed since symfony/runtime is a Composer plugin that runs while dumping
+# the autoload file.
+# We skip it if autoload_runtime.php already exists, to avoid running composer
+# as root during `sudo make install-domserver`.
+composer-dump-autoload: vendor/autoload_runtime.php
+
+vendor/autoload_runtime.php:
+	composer $(subst 1,-q,$(QUIET)) dump-autoload -o -a
+
+composer-dump-autoload-dev:
+	composer $(subst 1,-q,$(QUIET)) dump-autoload
 
 # Run Symfony in dev mode (for maintainer-mode):
 .env.local:
@@ -18,9 +43,6 @@ maintainer-conf: .env.local
 	@echo "# the DOMjudge Symfony application in developer mode. Adjust as needed." >> $@
 	@echo "APP_ENV=dev" >> $@
 
-composer-dump-autoload-dev:
-	composer $(subst 1,-q,$(QUIET)) dump-autoload
-
 copy-bundle-assets:
 # We can not use bin/console here, as when using a fakeroot,
 # the include paths are broken. We just copy in the data we need
@@ -30,6 +52,7 @@ copy-bundle-assets:
 
 clean-l:
 	-rm -rf public/bundles/nelmioapidoc
+	-rm -f vendor/autoload_runtime.php
 
 install-domserver:
 # This must be done first to install with the rest.
@@ -52,24 +75,9 @@ install-domserver:
 	done
 	$(INSTALL_DATA) -t $(DESTDIR)$(domserver_webappdir) phpunit.xml.dist .env
 
-inplace-install: composer-autoclean
-maintainer-install: composer-dump-autoload-dev
-
-# Install PHP dependencies
-composer-dependencies:
-ifeq (, $(shell command -v composer 2> /dev/null))
-	$(error "'composer' command not found in $(PATH), install it via your package manager or https://getcomposer.org/download/")
-endif
-# We use --no-scripts here because at this point the autoload.php file is
-# not generated yet, which is needed to run the post-install scripts.
-	composer $(subst 1,-q,$(QUIET)) install --prefer-dist -o -a --no-scripts --no-plugins
-
-composer-dependencies-dev:
-	composer $(subst 1,-q,$(QUIET)) install --prefer-dist --no-scripts --no-plugins
+maintainer-conf: .env.local
 
-composer-autoclean:
-# Make sure we're running from a clean state:
-	composer auto-scripts
+maintainer-install: composer-dump-autoload-dev
 
 maintainer-clean-l:
 	-for d in cache log ; do \
@@ -78,4 +86,5 @@ maintainer-clean-l:
 		done ; \
 	done
 
-.PHONY: copy-bundle-assets
+.PHONY: composer-dump-autoload composer-dump-autoload-dev \
+        copy-bundle-assets
diff --git a/webapp/vendor/Makefile b/webapp/vendor/Makefile
deleted file mode 100644
index 210d2e6c57..0000000000
--- a/webapp/vendor/Makefile
+++ /dev/null
@@ -1,12 +0,0 @@
-ifndef TOPDIR
-TOPDIR=../..
-endif
-include $(TOPDIR)/Makefile.global
-
-clean-l:
-	rm -f autoload_runtime.php
-
-autoload_runtime.php:
-	composer $(subst 1,-q,$(QUIET)) dump-autoload -o -a -d ..
-
-domserver: autoload_runtime.php