diff --git a/ucs-school-umc-installer/umc/python/schoolinstaller/__init__.py b/ucs-school-umc-installer/umc/python/schoolinstaller/__init__.py
index b7d8fd1..fefa8da 100644
--- a/ucs-school-umc-installer/umc/python/schoolinstaller/__init__.py
+++ b/ucs-school-umc-installer/umc/python/schoolinstaller/__init__.py
@@ -45,6 +45,7 @@
 import select
 import errno
 from httplib import HTTPException
+from distutils.version import LooseVersion
 
 import notifier
 import notifier.threads
@@ -538,6 +539,13 @@ def install(self, request):
 			if server_role == 'domaincontroller_backup' and not joined:
 				raise SchoolInstallerError(_('In order to install UCS@school on a backup domain controller, the system needs to be joined first.'))
 
+			school_version = masterinfo.get('school_version')
+			local_school_version = self.get_school_version()
+			if not school_version or LooseVersion(school_version) < LooseVersion(local_school_version):
+				if not ucr.is_true('ucsschool/join/ignore-version-mismatch/%s/%s' % (school_version, local_school_version)):
+					raise SchoolInstallerError(_('The version of the UCS@school app on the DC master is lower than the version on this host. Please consult the Univention Support Database on how to proceed: http://sdb.univention.de/1373'))
+				MODULE.warn('Ignoring UCS@school version mismatch: Master: %s; Local: %s;' % (school_version, local_school_version))
+
 		# everything ok, try to acquire the lock for the package installation
 		lock_aquired = self.package_manager.lock(raise_on_fail=False)
 		if not lock_aquired: