diff --git a/ext/debian/puppetmaster-passenger.postinst b/ext/debian/puppetmaster-passenger.postinst
index b21af7f61..2c9f20c3f 100644
--- a/ext/debian/puppetmaster-passenger.postinst
+++ b/ext/debian/puppetmaster-passenger.postinst
@@ -1,96 +1,112 @@
 #!/bin/sh
 
 set -e
 
 sitename="puppetmaster"
 
 # The debian provided a2* utils in Apache 2.4 uses "site name" as
 # argument, while the version in Apache 2.2 uses "file name".
 #
 # For added fun, the Apache 2.4 version requires files to have a
 # ".conf" suffix, but this must be stripped when using it as argument
 # for the a2* utilities.
 #
 # This will end in tears…
 # Can be removed when we only support apache >= 2.4
 apache2_puppetmaster_sitename() {
     apache2_version="$(dpkg-query --showformat='${Version}\n' --show apache2)"
     if dpkg --compare-versions "$apache2_version" gt "2.4~"; then
         echo "${sitename}.conf"
     else
         echo "${sitename}"
     fi
 }
 
 # Can be removed when we only support apache >= 2.4
 restart_apache2() {
     if [ -x "/etc/init.d/apache2" ]; then
         # Seems that a restart is needed. reload breaks ssl apparently.
         if [ -x "`which invoke-rc.d 2>/dev/null`" ]; then
             invoke-rc.d apache2 restart || exit $?
         else
             /etc/init.d/apache2 restart || exit $?
         fi
     fi
 }
 
+# We may need to update the passenger directives in the apache vhost because
+# RailsAutoDetect and RackAutoDetect were removed in passenger 4.0.0
+#       see http://www.modrails.com/documentation/Users%20guide%20Apache.html#_railsautodetect_rackautodetect_and_wsgiautodetect
+update_vhost_for_passenger4() {
+    # Get passenger version from dpkg.
+    # This will end in tears…
+    passenger_version="$(dpkg-query --showformat='${Version}\n' --show libapache2-mod-passenger)"
+    if dpkg --compare-versions "$passenger_version" gt "4.0~"; then
+        sed -r -i \
+            -e "/RailsAutoDetect/d" \
+            -e "/RackAutoDetect/d" \
+            $tempfile
+    fi
+}
+
 if [ "$1" = "configure" ]; then
 
     # Change the owner of the rack config.ru to be the puppet user
     # because passenger will suid to that user, see #577366
     if ! dpkg-statoverride --list /usr/share/puppet/rack/puppetmasterd/config.ru >/dev/null 2>&1
     then
         dpkg-statoverride --update --add puppet puppet 0644 /usr/share/puppet/rack/puppetmasterd/config.ru
     fi
     # Setup passenger configuration
     if [ "$2" = "" ]; then
 
         # Check that puppet master --configprint works properly
         # If it doesn't the following steps to update the vhost will produce a very unhelpful and broken vhost
         if [ $(puppet master --configprint all 2>&1 | grep "Could not parse" | wc -l) != "0" ]; then
             echo "Puppet config print not working properly, exiting"
             exit 1
         fi
 
         # Initialize puppetmaster CA and generate the master certificate
         # only if the host doesn't already have any puppet ssl certificate.
         # The ssl key and cert need to be available (eg generated) before
         # apache2 is configured and started since apache2 ssl configuration
         # uses the puppetmaster ssl files.
         if [ ! -e "$(puppet master --configprint hostcert)" ]; then
             puppet cert generate $(puppet master --configprint certname)
         fi
 
         # Setup apache2 configuration files
         APACHE2_SITE_FILE="/etc/apache2/sites-available/$(apache2_puppetmaster_sitename)"
         if  [ ! -e "${APACHE2_SITE_FILE}" ]; then
             tempfile=$(mktemp)
             sed -r \
                 -e "s|(SSLCertificateFile\s+).+$|\1$(puppet master --configprint hostcert)|" \
                 -e "s|(SSLCertificateKeyFile\s+).+$|\1$(puppet master --configprint hostprivkey)|" \
                 -e "s|(SSLCACertificateFile\s+).+$|\1$(puppet master --configprint localcacert)|" \
                 -e "s|(SSLCertificateChainFile\s+).+$|\1$(puppet master --configprint localcacert)|" \
                 -e "s|(SSLCARevocationFile\s+).+$|\1$(puppet master --configprint cacrl)|" \
                 -e "s|DocumentRoot /etc/puppet/rack/public|DocumentRoot /usr/share/puppet/rack/puppetmasterd/public|" \
                 -e "s|<Directory /etc/puppet/rack/>|<Directory /usr/share/puppet/rack/puppetmasterd/>|" \
                 /usr/share/puppetmaster-passenger/apache2.site.conf.tmpl > $tempfile
+            update_vhost_for_passenger4
             mv $tempfile "${APACHE2_SITE_FILE}"
         fi
 
         # Enable needed modules
         a2enmod ssl
         a2enmod headers
         a2ensite ${sitename}
         restart_apache2
     fi
 
     # Fix CRL file on upgrade to use the CA crl file instead of the host crl.
     if dpkg --compare-versions "$2" lt-nl "2.6.1-1"; then
         if [ -e /etc/apache2/sites-available/puppetmaster ]; then
             sed -r -i 's|SSLCARevocationFile[[:space:]]+/var/lib/puppet/ssl/crl.pem$|SSLCARevocationFile /var/lib/puppet/ssl/ca/ca_crl.pem|' /etc/apache2/sites-available/puppetmaster
             restart_apache2
         fi
     fi
 fi
 
 #DEBHELPER#