diff --git a/support/packager/build.sh b/support/packager/build.sh
index e889f2978..9206b4d33 100755
--- a/support/packager/build.sh
+++ b/support/packager/build.sh
@@ -1,48 +1,51 @@
 #!/usr/bin/env bash
 # Build a fresh Mediawiki-Vagrant installer image
+#
+# Meant to be executed inside the Vagrant virtual machine
+#
+# Requires:
+#   - aptitude
+#   - genisoimage
 
-VAGRANT=/srv/vagrant
-CONTENTS=$VAGRANT/support/packager/output/contents
+MWV=/vagrant
+CONTENTS=${MWV}/support/packager/output/contents
 
 # Get latest MediaWiki-Vagrant
-cd $VAGRANT
+cd ${MWV}
 git fetch
 git reset --hard origin/master
 
 # Get latest MediaWiki-core
-export COMPOSER_CACHE_DIR="$VAGRANT/cache/composer"
-/bin/labs-vagrant git-update
-cd $VAGRANT/mediawiki
+export COMPOSER_CACHE_DIR="${MWV}/cache/composer"
+/usr/local/bin/run-git-update
+cd ${MWV}/mediawiki
 git reset --hard origin/master
 
-# Run puppet to fill caches
-/bin/labs-vagrant provision
-
 # Freshen git cache
 sudo apt-get update
 sudo aptitiude dist-upgrade
 # Get rid of obsolete apt packages
 sudo aptitude autoclean
 
 # Hack some things into the build
-mkdir -p $CONTENTS
+mkdir -p ${CONTENTS}
 
 # Add a BUILD_INFO file so we can tell what was included in the image
-BUILD_INFO=$CONTENTS/BUILD_INFO
-echo "Build date: $(date +%Y-%m-%dT%H:%MZ)" >$BUILD_INFO
-echo "MediaWiki-Vagrant: $(cd /vagrant; git rev-parse HEAD)" >>$BUILD_INFO
-echo "MediaWiki: $(cd /vagrant/mediawiki; git rev-parse HEAD)" >>$BUILD_INFO
+BUILD_INFO=${CONTENTS}/BUILD_INFO
+echo "Build date: $(date +%Y-%m-%dT%H:%MZ)" >${BUILD_INFO}
+echo "MediaWiki-Vagrant: $(cd ${MWV}; git rev-parse HEAD)" >>${BUILD_INFO}
+echo "MediaWiki: $(cd ${MWV}/mediawiki; git rev-parse HEAD)" >>${BUILD_INFO}
 
 # Populate apt cache
-mkdir -p $CONTENTS/cache/apt/partial
-rm -rf $CONTENTS/cache/apt/*.deb
-(cd /var/cache/apt/archives; tar cf - *.deb) |
-(cd $CONTENTS/cache/apt; tar xf -)
+mkdir -p ${CONTENTS}/cache/apt/partial
+rm -rf ${CONTENTS}/cache/apt/*.deb
+(cd /vagrant/cache/apt/archives; tar cf - *.deb) |
+(cd ${CONTENTS}/cache/apt; tar xf -)
 
 # Generate installer output (directory and iso)
-cd $VAGRANT/support/packager
+cd ${MWV}/support/packager
 ruby package.rb
 
 # Compute and store a checksum for the image
-cd $VAGRANT/support/packager/output
+cd ${MWV}/support/packager/output
 sha1sum mediawiki-vagrant-installer.iso > mediawiki-vagrant-installer.iso.SHA1.txt