diff --git a/library/Director/Objects/GroupMembershipResolver.php b/library/Director/Objects/GroupMembershipResolver.php
new file mode 100644
index 00000000..2507813e
--- /dev/null
+++ b/library/Director/Objects/GroupMembershipResolver.php
@@ -0,0 +1,509 @@
+<?php
+
+namespace Icinga\Module\Director\Objects;
+
+use Icinga\Application\Benchmark;
+use Icinga\Data\Filter\Filter;
+use Icinga\Exception\ProgrammingError;
+use Icinga\Module\Director\Db;
+use Zend_Db_Select as ZfSelect;
+
+/**
+ * Class GroupMembershipResolver
+ *
+ * - Fetches all involved assignments
+ * - Fetch all (or one) object
+ * - Fetch all (or one) group
+ */
+abstract class GroupMembershipResolver
+{
+    /** @var string Object type, 'host', 'service', 'user' or similar */
+    protected $type;
+
+    /** @var array */
+    protected $existingMappings;
+
+    /** @var array */
+    protected $newMappings;
+
+    /** @var Db */
+    protected $connection;
+
+    /** @var \Zend_Db_Adapter_Abstract */
+    protected $db;
+
+    /** @var IcingaObject[] */
+    protected $objects;
+
+    /** @var IcingaObjectGroup[] */
+    protected $groups = array();
+
+    /** @var bool */
+    protected $deferred = false;
+
+    /** @var bool */
+    protected $useTransactions = false;
+
+    public function __construct(Db $connection)
+    {
+        $this->connection = $connection;
+        $this->db = $connection->getDbAdapter();
+    }
+
+    /**
+     * @return $this
+     */
+    public function refreshAllMappings()
+    {
+        return $this->clearGroups()->clearObjects()->refreshDb(true);
+    }
+
+    /**
+     * @param bool $force
+     * @return $this
+     */
+    public function refreshDb($force = false)
+    {
+        if ($force || ! $this->isDeferred()) {
+            Benchmark::measure('Going to refresh all group mappings');
+            $this->fetchStoredMappings();
+            Benchmark::measure('Got stored HG mappings, rechecking all objects');
+            $this->recheckAllObjects($this->getAppliedGroups());
+            Benchmark::measure('Ready, going to store new mappings');
+            $this->storeNewMappings();
+            $this->removeOutdatedMappings();
+        }
+
+        return $this;
+    }
+
+    /**
+     * @param bool $defer
+     * @return $this
+     */
+    public function defer($defer = true)
+    {
+        $this->deferred = $defer;
+        return $this;
+    }
+
+    /**
+     * @param $use
+     * @return $this
+     */
+    public function setUseTransactions($use)
+    {
+        $this->useTransactions = $use;
+        return $this;
+    }
+
+    public function getType()
+    {
+        if ($this->type === null) {
+            throw new ProgrammingError(
+                '"type" is required when extending %s, got none in %s',
+                __CLASS__,
+                get_class($this)
+            );
+        }
+
+        return $this->type;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isDeferred()
+    {
+        return $this->deferred;
+    }
+
+    /**
+     * @param IcingaObject $object
+     * @return $this
+     */
+    public function addObject(IcingaObject $object)
+    {
+        $this->assertBeenLoadedFromDb($object);
+        if ($this->objects === null) {
+            $this->objects = array();
+        }
+
+        $this->objects[$object->get('id')] = $object;
+        return $this;
+    }
+
+    /**
+     * @param IcingaObject[] $objects
+     * @return $this
+     */
+    public function addObjects(array $objects)
+    {
+        foreach ($objects as $object) {
+            $this->addObject($object);
+        }
+
+        return $this;
+    }
+
+    /**
+     * @param IcingaObject $object
+     * @return $this
+     */
+    public function setObject(IcingaObject $object)
+    {
+        $this->clearObjects();
+        return $this->addObject($object);
+    }
+
+    /**
+     * @param IcingaObject[] $objects
+     * @return $this
+     */
+    public function setObjects(array $objects)
+    {
+        $this->clearObjects();
+        return $this->addObjects($objects);
+    }
+
+    /**
+     * @return $this
+     */
+    public function clearObjects()
+    {
+        $this->objects = array();
+        return $this;
+    }
+
+    /**
+     * @param IcingaObjectGroup $group
+     * @return $this
+     */
+    public function addGroup(IcingaObjectGroup $group)
+    {
+        $this->assertBeenLoadedFromDb($group);
+
+        if ($group->get('assign_filter') !== null) {
+            $this->groups[$group->get('id')] = $group;
+        }
+
+        return $this;
+    }
+
+    /**
+     * @param IcingaObjectGroup[] $groups
+     * @return $this
+     */
+    public function addGroups(array $groups)
+    {
+        foreach ($groups as $group) {
+            $this->addGroup($group);
+        }
+
+        return $this;
+    }
+
+    /**
+     * @param IcingaObjectGroup $group
+     * @return $this
+     */
+    public function setGroup(IcingaObjectGroup $group)
+    {
+        $this->clearGroups();
+        return $this->addGroup($group);
+    }
+
+    /**
+     * @param array $groups
+     * @return $this
+     */
+    public function setGroups(array $groups)
+    {
+        $this->clearGroups();
+        return $this->addGroups($groups);
+    }
+
+    /**
+     * @return $this
+     */
+    public function clearGroups()
+    {
+        $this->objects = array();
+        return $this;
+    }
+
+    protected function storeNewMappings()
+    {
+        $diff = $this->getDifference($this->newMappings, $this->existingMappings);
+        $count = count($diff);
+        if ($count === 0) {
+            return;
+        }
+
+        $db = $this->db;
+        $this->beginTransaction();
+        foreach ($diff as $row) {
+            $db->insert(
+                $this->getResolvedTableName(),
+                $row
+            );
+        }
+
+        $this->commit();
+        Benchmark::measure(
+            sprintf(
+                'Stored %d new resolved group memberships',
+                $count
+            )
+        );
+    }
+
+    protected function removeOutdatedMappings()
+    {
+        $diff = $this->getDifference($this->existingMappings, $this->newMappings);
+        $count = count($diff);
+        if ($count === 0) {
+            return;
+        }
+
+        $type = $this->getType();
+        $db = $this->db;
+        $this->beginTransaction();
+        foreach ($diff as $row) {
+            $db->delete(
+                $this->getResolvedTableName(),
+                sprintf(
+                    "(${type}group_id = %d AND ${type}_id = %d)",
+                    $row["${type}group_id"],
+                    $row["${type}_id"]
+                )
+            );
+        }
+
+        $this->commit();
+        Benchmark::measure(
+            sprintf(
+                'Removed %d outdated group memberships',
+                $count
+            )
+        );
+    }
+
+    protected function getDifference(& $left, & $right)
+    {
+        $diff = array();
+
+        $type = $this->getType();
+        foreach ($left as $groupId => $objectIds) {
+            if (array_key_exists($groupId, $right)) {
+                foreach ($objectIds as $objectId) {
+                    if (! array_key_exists($objectId, $right[$groupId])) {
+                        $diff[] = array(
+                            "${type}group_id" => $groupId,
+                            "${type}_id"      => $objectId,
+                        );
+                    }
+                }
+            } else {
+                foreach ($objectIds as $objectId) {
+                    $diff[] = array(
+                        "${type}group_id" => $groupId,
+                        "${type}_id"      => $objectId,
+                    );
+                }
+            }
+        }
+
+        return $diff;
+    }
+
+    protected function fetchStoredMappings()
+    {
+        $mappings = array();
+
+        $type = $this->getType();
+        $query = $this->db->select()->from(
+            array('hgh' => $this->getResolvedTableName()),
+            array(
+                'group_id'  => "${type}group_id",
+                'object_id' => "${type}_id",
+            )
+        );
+        $this->addMembershipWhere($query, "${type}_id", $this->objects);
+        $this->addMembershipWhere($query, "${type}group_id", $this->groups);
+
+        foreach ($this->db->fetchAll($query) as $row) {
+            $groupId = $row->group_id;
+            $objectId = $row->object_id;
+            if (! array_key_exists($groupId, $mappings)) {
+                $mappings[$groupId] = array();
+            }
+
+            $mappings[$groupId][$objectId] = $objectId;
+        }
+
+        $this->existingMappings = $mappings;
+    }
+
+    /**
+     * @param ZfSelect $query
+     * @param string $column
+     * @param IcingaObject[] $objects
+     * @return ZfSelect
+     */
+    protected function addMembershipWhere(ZfSelect $query, $column, & $objects)
+    {
+        if (empty($objects)) {
+            return $query;
+        }
+
+        $ids = array();
+        foreach ($objects as $object) {
+            $ids[] = (int) $object->get('id');
+        }
+
+        if (count($ids) === 1) {
+            $query->orWhere($column . ' = ?', $ids[0]);
+        } else {
+            $query->orWhere($column . ' IN (?)', $ids);
+        }
+
+        return $query;
+    }
+
+    protected function recheckAllObjects($groups)
+    {
+        $mappings = array();
+
+        foreach ($this->getObjects() as $object) {
+            // TODO: fix this last hard host dependency
+            $resolver = HostApplyMatches::prepare($object);
+            foreach ($groups as $groupId => $filter) {
+                if ($resolver->matchesFilter(Filter::fromQueryString($filter))) {
+                    if (! array_key_exists($groupId, $mappings)) {
+                        $mappings[$groupId] = array();
+                    }
+
+                    $id = $object->get('id');
+                    $mappings[$groupId][$id] = $id;
+                }
+            }
+        }
+
+        foreach ($this->fetchMissingSingleAssignments() as $row) {
+            $mappings[$row->group_id][$row->object_id] = $row->object_id;
+        }
+
+        $this->newMappings = $mappings;
+    }
+
+    protected function getAppliedGroups()
+    {
+        if (empty($this->groups)) {
+            return $this->fetchAppliedGroups();
+        } else {
+            return $this->buildAppliedGroups();
+        }
+    }
+
+    protected function buildAppliedGroups()
+    {
+        $list = array();
+        foreach ($this->groups as $id => $group) {
+            $list[$id] = $group->get('assign_filter');
+        }
+
+        return $list;
+    }
+
+    protected function fetchAppliedGroups()
+    {
+        $type = $this->getType();
+        $query = $this->db->select()->from(
+            array('hg' => "icinga_${type}group"),
+            array(
+                'id',
+                'assign_filter',
+            )
+        )->where('assign_filter IS NOT NULL');
+
+        return $this->db->fetchPairs($query);
+    }
+
+    protected function fetchMissingSingleAssignments()
+    {
+        $type = $this->getType();
+        $query = $this->db->select()->from(
+            array("go" => $this->getTableName()),
+            array(
+                'object_id' => "${type}_id",
+                'group_id'  => "${type}group_id",
+            )
+        )->joinLeft(
+            array("gor" => $this->getResolvedTableName()),
+            "go.${type}_id = gor.${type}_id AND go.${type}group_id = gor.${type}group_id",
+            array()
+        )->where("hghr.${type}_id IS NULL");
+
+        $this->addMembershipWhere($query, "go.${type}_id", $this->objects);
+        $this->addMembershipWhere($query, "go.${type}group_id", $this->groups);
+
+        return $this->db->fetchAll($query);
+    }
+
+    protected function getTableName()
+    {
+        $type = $this->getType();
+        return "icinga_${type}group_${type}";
+    }
+
+    protected function getResolvedTableName()
+    {
+        return $this->getTableName() . '_resolved';
+    }
+
+    /**
+     * @return $this
+     */
+    protected function beginTransaction()
+    {
+        if ($this->useTransactions) {
+            $this->db->beginTransaction();
+        }
+
+        return $this;
+    }
+
+    /**
+     * @return $this
+     */
+    protected function commit()
+    {
+        if ($this->useTransactions) {
+            $this->db->commit();
+        }
+
+        return $this;
+    }
+
+    /**
+     * @return IcingaObject[]
+     */
+    protected function getObjects()
+    {
+        if ($this->objects === null) {
+            $this->objects = IcingaObject::loadAllByType($this->getType(), $this->connection);
+        }
+
+        return $this->objects;
+    }
+
+    protected function assertBeenLoadedFromDb(IcingaObject $object)
+    {
+        if (! ctype_digit($object->get('id'))) {
+            throw new ProgrammingError(
+                'Group resolver does not support unstored objects'
+            );
+        }
+    }
+}
diff --git a/library/Director/Objects/HostGroupMembershipResolver.php b/library/Director/Objects/HostGroupMembershipResolver.php
index 13f6293b..b5970178 100644
--- a/library/Director/Objects/HostGroupMembershipResolver.php
+++ b/library/Director/Objects/HostGroupMembershipResolver.php
@@ -2,477 +2,7 @@
 
 namespace Icinga\Module\Director\Objects;
 
-use Icinga\Application\Benchmark;
-use Icinga\Data\Filter\Filter;
-use Icinga\Exception\ProgrammingError;
-use Icinga\Module\Director\Db;
-use Zend_Db_Select as ZfSelect;
-
-/**
- * Class HostGroupMembershipResolver
- *
- * - Fetches all involved assignments
- * - Fetch all (or one) host
- * - Fetch all (or one) group
- */
-class HostGroupMembershipResolver
+class HostGroupMembershipResolver extends GroupMembershipResolver
 {
-    /** @var array */
-    protected $existingMappings;
-
-    /** @var array */
-    protected $newMappings;
-
-    /** @var Db */
-    protected $connection;
-
-    /** @var \Zend_Db_Adapter_Abstract */
-    protected $db;
-
-    /** @var IcingaHost[] */
-    protected $hosts;
-
-    /** @var IcingaHostGroup[] */
-    protected $hostgroups = array();
-
-    protected $table = 'icinga_hostgroup_host_resolved';
-
-    /** @var bool */
-    protected $deferred = false;
-
-    /** @var bool */
-    protected $useTransactions = false;
-
-    public function __construct(Db $connection)
-    {
-        $this->connection = $connection;
-        $this->db = $connection->getDbAdapter();
-    }
-
-    /**
-     * @return $this
-     */
-    public function refreshAllMappings()
-    {
-        return $this->clearHostgroups()->clearHosts()->refreshDb(true);
-    }
-
-    /**
-     * @param bool $force
-     * @return $this
-     */
-    public function refreshDb($force = false)
-    {
-        if ($force || ! $this->isDeferred()) {
-            Benchmark::measure('Going to refresh all hostgroup mappings');
-            $this->fetchStoredMappings();
-            Benchmark::measure('Got stored HG mappings, rechecking all hosts');
-            $this->recheckAllHosts($this->getAppliedHostgroups());
-            Benchmark::measure('Ready, going to store new mappings');
-            $this->storeNewMappings();
-            $this->removeOutdatedMappings();
-        }
-
-        return $this;
-    }
-
-    /**
-     * @param bool $defer
-     * @return $this
-     */
-    public function defer($defer = true)
-    {
-        $this->deferred = $defer;
-        return $this;
-    }
-
-    /**
-     * @param $use
-     * @return $this
-     */
-    public function setUseTransactions($use)
-    {
-        $this->useTransactions = $use;
-        return $this;
-    }
-
-    /**
-     * @return bool
-     */
-    public function isDeferred()
-    {
-        return $this->deferred;
-    }
-
-    /**
-     * @param IcingaHost $host
-     * @return $this
-     */
-    public function addHost(IcingaHost $host)
-    {
-        $this->assertBeenLoadedFromDb($host);
-        if ($this->hosts === null) {
-            $this->hosts = array();
-        }
-
-        $this->hosts[$host->get('id')] = $host;
-        return $this;
-    }
-
-    /**
-     * @param IcingaHost[] $hosts
-     * @return $this
-     */
-    public function addHosts(array $hosts)
-    {
-        foreach ($hosts as $host) {
-            $this->addHost($host);
-        }
-
-        return $this;
-    }
-
-    /**
-     * @param IcingaHost $host
-     * @return $this
-     */
-    public function setHost(IcingaHost $host)
-    {
-        $this->clearHosts();
-        return $this->addHost($host);
-    }
-
-    /**
-     * @param IcingaHost[] $hosts
-     * @return $this
-     */
-    public function setHosts(array $hosts)
-    {
-        $this->clearHosts();
-        return $this->addHosts($hosts);
-    }
-
-    /**
-     * @return $this
-     */
-    public function clearHosts()
-    {
-        $this->hosts = array();
-        return $this;
-    }
-
-    /**
-     * @param IcingaHostGroup $group
-     * @return $this
-     */
-    public function addHostgroup(IcingaHostGroup $group)
-    {
-        $this->assertBeenLoadedFromDb($group);
-
-        if ($group->get('assign_filter') !== null) {
-            $this->hostgroups[$group->get('id')] = $group;
-        }
-
-        return $this;
-    }
-
-    /**
-     * @param IcingaHostGroup[] $groups
-     * @return $this
-     */
-    public function addHostgroups(array $groups)
-    {
-        foreach ($groups as $group) {
-            $this->addHostgroup($group);
-        }
-
-        return $this;
-    }
-
-    /**
-     * @param IcingaHostGroup $group
-     * @return $this
-     */
-    public function setHostgroup(IcingaHostGroup $group)
-    {
-        $this->clearHostgroups();
-        return $this->addHostgroup($group);
-    }
-
-    /**
-     * @param array $groups
-     * @return $this
-     */
-    public function setHostgroups(array $groups)
-    {
-        $this->clearHostgroups();
-        return $this->addHostgroups($groups);
-    }
-
-    /**
-     * @return $this
-     */
-    public function clearHostgroups()
-    {
-        $this->hosts = array();
-        return $this;
-    }
-
-    protected function storeNewMappings()
-    {
-        $diff = $this->getDifference($this->newMappings, $this->existingMappings);
-        $count = count($diff);
-        if ($count === 0) {
-            return;
-        }
-
-        $db = $this->db;
-        $this->beginTransaction();
-        foreach ($diff as $row) {
-            $db->insert(
-                $this->table,
-                $row
-            );
-        }
-
-        $this->commit();
-        Benchmark::measure(
-            sprintf(
-                'Stored %d new resolved hostgroup memberships',
-                $count
-            )
-        );
-    }
-
-    protected function removeOutdatedMappings()
-    {
-        $diff = $this->getDifference($this->existingMappings, $this->newMappings);
-        $count = count($diff);
-        if ($count === 0) {
-            return;
-        }
-
-        $db = $this->db;
-        $this->beginTransaction();
-        foreach ($diff as $row) {
-            $db->delete(
-                $this->table,
-                sprintf(
-                    '(hostgroup_id = %d AND host_id = %d)',
-                    $row['hostgroup_id'],
-                    $row['host_id']
-                )
-            );
-        }
-
-        $this->commit();
-        Benchmark::measure(
-            sprintf(
-                'Removed %d outdated hostgroup memberships',
-                $count
-            )
-        );
-    }
-
-    protected function getDifference(& $left, & $right)
-    {
-        $diff = array();
-
-        foreach ($left as $groupId => $hostIds) {
-            if (array_key_exists($groupId, $right)) {
-                foreach ($hostIds as $hostId) {
-                    if (! array_key_exists($hostId, $right[$groupId])) {
-                        $diff[] = array(
-                            'hostgroup_id' => $groupId,
-                            'host_id'      => $hostId,
-                        );
-                    }
-                }
-            } else {
-                foreach ($hostIds as $hostId) {
-                    $diff[] = array(
-                        'hostgroup_id' => $groupId,
-                        'host_id'      => $hostId,
-                    );
-                }
-            }
-        }
-
-        return $diff;
-    }
-
-    protected function fetchStoredMappings()
-    {
-        $mappings = array();
-
-        $query = $this->db->select()->from(
-            array('hgh' => $this->table),
-            array(
-                'hostgroup_id',
-                'host_id',
-            )
-        );
-        $this->addMembershipWhere($query, 'host_id', $this->hosts);
-        $this->addMembershipWhere($query, 'hostgroup_id', $this->hostgroups);
-
-        foreach ($this->db->fetchAll($query) as $row) {
-            $groupId = $row->hostgroup_id;
-            $hostId = $row->host_id;
-            if (! array_key_exists($groupId, $mappings)) {
-                $mappings[$groupId] = array();
-            }
-
-            $mappings[$groupId][$hostId] = $hostId;
-        }
-
-        $this->existingMappings = $mappings;
-    }
-
-    /**
-     * @param ZfSelect $query
-     * @param string $column
-     * @param IcingaObject[] $objects
-     * @return ZfSelect
-     */
-    protected function addMembershipWhere(ZfSelect $query, $column, & $objects)
-    {
-        if (empty($objects)) {
-            return $query;
-        }
-
-        $ids = array();
-        foreach ($objects as $object) {
-            $ids[] = (int) $object->get('id');
-        }
-
-        if (count($ids) === 1) {
-            $query->orWhere($column . ' = ?', $ids[0]);
-        } else {
-            $query->orWhere($column . ' IN (?)', $ids);
-        }
-
-        return $query;
-    }
-
-    protected function recheckAllHosts($groups)
-    {
-        $mappings = array();
-
-        foreach ($this->getHosts() as $host) {
-            $resolver = HostApplyMatches::prepare($host);
-            foreach ($groups as $groupId => $filter) {
-                if ($resolver->matchesFilter(Filter::fromQueryString($filter))) {
-                    if (! array_key_exists($groupId, $mappings)) {
-                        $mappings[$groupId] = array();
-                    }
-
-                    $id = $host->get('id');
-                    $mappings[$groupId][$id] = $id;
-                }
-            }
-        }
-
-        foreach ($this->fetchMissingSingleAssignments() as $row) {
-            $mappings[$row->hostgroup_id][$row->host_id] = $row->host_id;
-        }
-
-        $this->newMappings = $mappings;
-    }
-
-    protected function getAppliedHostgroups()
-    {
-        if (empty($this->hostgroups)) {
-            return $this->fetchAppliedHostgroups();
-        } else {
-            return $this->buildAppliedHostgroups();
-        }
-    }
-
-    protected function buildAppliedHostgroups()
-    {
-        $list = array();
-        foreach ($this->hostgroups as $id => $group) {
-            $list[$id] = $group->get('assign_filter');
-        }
-
-        return $list;
-    }
-
-    protected function fetchAppliedHostgroups()
-    {
-        $query = $this->db->select()->from(
-            array('hg' => 'icinga_hostgroup'),
-            array(
-                'id',
-                'assign_filter',
-            )
-        )->where('assign_filter IS NOT NULL');
-
-        return $this->db->fetchPairs($query);
-    }
-
-    protected function fetchMissingSingleAssignments()
-    {
-        $query = $this->db->select()->from(
-            array('hgh' => 'icinga_hostgroup_host'),
-            array(
-                'host_id',
-                'hostgroup_id',
-            )
-        )->joinLeft(
-            array('hghr' => 'icinga_hostgroup_host_resolved'),
-            'hgh.host_id = hghr.host_id AND hgh.hostgroup_id = hghr.hostgroup_id',
-            array()
-        )->where('hghr.host_id IS NULL');
-
-        $this->addMembershipWhere($query, 'hgh.host_id', $this->hosts);
-        $this->addMembershipWhere($query, 'hgh.hostgroup_id', $this->hostgroups);
-
-        return $this->db->fetchAll($query);
-    }
-
-    /**
-     * @return $this
-     */
-    protected function beginTransaction()
-    {
-        if ($this->useTransactions) {
-            $this->db->beginTransaction();
-        }
-
-        return $this;
-    }
-
-    /**
-     * @return $this
-     */
-    protected function commit()
-    {
-        if ($this->useTransactions) {
-            $this->db->commit();
-        }
-
-        return $this;
-    }
-
-    /**
-     * @return IcingaHost[]
-     */
-    protected function getHosts()
-    {
-        if ($this->hosts === null) {
-            $this->hosts = IcingaHost::loadAll($this->connection);
-        }
-
-        return $this->hosts;
-    }
-
-    protected function assertBeenLoadedFromDb(IcingaObject $object)
-    {
-        if (! ctype_digit($object->get('id'))) {
-            throw new ProgrammingError(
-                'Hostgroup resolver does not support unstored objects'
-            );
-        }
-    }
+    protected $type = 'host';
 }
diff --git a/library/Director/Objects/IcingaHost.php b/library/Director/Objects/IcingaHost.php
index 2e43ab20..65879aa4 100644
--- a/library/Director/Objects/IcingaHost.php
+++ b/library/Director/Objects/IcingaHost.php
@@ -298,7 +298,7 @@ class IcingaHost extends IcingaObject
     protected function notifyResolvers()
     {
         $resolver = $this->getHostGroupMembershipResolver();
-        $resolver->addHost($this);
+        $resolver->addObject($this);
         $resolver->refreshDb();
 
         return $this;
diff --git a/library/Director/Objects/IcingaHostGroup.php b/library/Director/Objects/IcingaHostGroup.php
index 0d1ec0e0..b5cffafa 100644
--- a/library/Director/Objects/IcingaHostGroup.php
+++ b/library/Director/Objects/IcingaHostGroup.php
@@ -48,7 +48,7 @@ class IcingaHostGroup extends IcingaObjectGroup
     protected function notifyResolvers()
     {
         $resolver = $this->getHostGroupMembershipResolver();
-        $resolver->addHostgroup($this);
+        $resolver->addGroup($this);
         $resolver->refreshDb();
 
         return $this;