diff --git a/management/univention-directory-manager-modules/modules/univention/admin/handlers/__init__.py b/management/univention-directory-manager-modules/modules/univention/admin/handlers/__init__.py
index 502a589..65d7579 100644
--- a/management/univention-directory-manager-modules/modules/univention/admin/handlers/__init__.py
+++ b/management/univention-directory-manager-modules/modules/univention/admin/handlers/__init__.py
@@ -683,18 +683,8 @@ def _create(self):
 		# evaluate extended attributes
 		ocs = set()
 		for prop in getattr(m, 'extended_udm_attributes', []):
-			univention.debug.debug(univention.debug.ADMIN, univention.debug.INFO, 'simpleLdap._create: prop.objClass = %s, prop.name = %s'% (prop.objClass, prop.name))
-			if not self.info.get(prop.name):
-				continue
-			univention.debug.debug(univention.debug.ADMIN, univention.debug.INFO, 'simpleLdap._create: prop.name: info[%s] = %s'% (prop.name, self.info.get(prop.name)))
-
-			# do not add object class and value if syntax is boolean and checkbox is disabled
-			if prop.syntax == 'boolean' and self.info.get(prop.name) == '0':
-				al = [x for x in al if x[0].lower() != prop.ldapMapping.lower()]
-				continue
-
-			# in all other cases add object class
-			if self.has_key(prop.name):
+			univention.debug.debug(univention.debug.ADMIN, univention.debug.INFO, 'simpleLdap._create: info[%s]:%r = %r'% (prop.name, self.has_key(prop.name), self.info.get(prop.name)))
+			if self.has_key(prop.name) and self.info.get(prop.name):
 				ocs.add(prop.objClass)
 
 		# add object classes of (especially extended) options
@@ -805,14 +795,14 @@ def _ldap_object_classes(self, ml):
 		for prop in getattr(m, 'extended_udm_attributes', []):
 			univention.debug.debug(univention.debug.ADMIN, univention.debug.INFO, 'simpleLdap._modify: extended attribute=%r  oc=%r'% (prop.name, prop.objClass))
 
-			if self.__ea_value_is_set(prop.name):
+			if self.has_key(prop.name) and self.info.get(prop.name):
 				required_ocs |= set([prop.objClass])
 				continue
 
 			if prop.deleteObjClass:
 				unneeded_ocs |= set([prop.objClass])
 
-			# if the value is unset (or a boolean attribute with value == 0) we need to remove the attribute completely
+			# if the value is unset we need to remove the attribute completely
 			if self.oldattr.get(prop.ldapMapping):
 				ml = [x for x in ml if x[0].lower() != prop.ldapMapping.lower()]
 				ml.append((prop.ldapMapping, self.oldattr.get(prop.ldapMapping), ''))
@@ -868,13 +858,6 @@ def _ldap_object_classes(self, ml):
 
 		return ml
 
-	def __ea_value_is_set(self, name):
-		if not self.has_key(name):
-			return False
-		if self.descriptions[name].syntax == 'boolean' and self.info.get(name) == '0':
-			return False
-		return self.info.get(name)
-
 	def _move_in_subordinates(self, olddn):
 		result = self.lo.search(base=self.lo.base, filter=filter_format('(&(objectclass=person)(secretary=%s))', [olddn]), attr=['dn'])
 		for subordinate, attr in result:
diff --git a/management/univention-directory-manager-modules/modules/univention/admin/mapping.py b/management/univention-directory-manager-modules/modules/univention/admin/mapping.py
index 490eaf4..07d1cf9 100644
--- a/management/univention-directory-manager-modules/modules/univention/admin/mapping.py
+++ b/management/univention-directory-manager-modules/modules/univention/admin/mapping.py
@@ -149,6 +149,17 @@ def mapBase64(value):
 			univention.debug.debug(univention.debug.ADMIN, univention.debug.ERROR, 'ERROR in mapBase64: %s' % e)
 	return ""
 
+def BooleanListToString(list):
+	v = univention.admin.mapping.ListToString(list)
+	if v == '0':
+		return ''
+	return v
+
+def BooleanUnMap(value):
+	if value == '0':
+		return ''
+	return value
+
 class mapping:
 	def __init__(self):
 		self._map={}
diff --git a/management/univention-directory-manager-modules/modules/univention/admin/modules.py b/management/univention-directory-manager-modules/modules/univention/admin/modules.py
index 479dc49..b50db1e 100644
--- a/management/univention-directory-manager-modules/modules/univention/admin/modules.py
+++ b/management/univention-directory-manager-modules/modules/univention/admin/modules.py
@@ -320,9 +320,14 @@ def update_extended_attributes(lo, module, position):
 		if attrs.get('univentionUDMPropertyMultivalue', [''])[0] == '1':
 			multivalue = 1
 			map_method = None
+			unmap_method = None
 		else:
 			multivalue = 0
 			map_method = univention.admin.mapping.ListToString
+			unmap_method = None
+			if propertySyntaxString == 'boolean':
+				map_method = univention.admin.mapping.BooleanListToString
+				unmap_method = univention.admin.mapping.BooleanUnMap
 			# single value ==> use only first value
 			propertyDefault = propertyDefault[0]
 
@@ -362,7 +367,7 @@ def update_extended_attributes(lo, module, position):
 
 		# add LDAP mapping
 		if attrs['univentionUDMPropertyLdapMapping'][0].lower() != 'objectClass'.lower():
-			module.mapping.register(pname, attrs['univentionUDMPropertyLdapMapping'][0], None, map_method)
+			module.mapping.register(pname, attrs['univentionUDMPropertyLdapMapping'][0], unmap_method, map_method)
 		else:
 			module.mapping.register(pname, attrs['univentionUDMPropertyLdapMapping'][0], univention.admin.mapping.nothing, univention.admin.mapping.nothing)