diff --git a/library/Icingadb/Model/Customvar.php b/library/Icingadb/Model/Customvar.php
index 7019d56d..f568292f 100644
--- a/library/Icingadb/Model/Customvar.php
+++ b/library/Icingadb/Model/Customvar.php
@@ -9,8 +9,6 @@ use ipl\Orm\Relations;
 
 class Customvar extends Model
 {
-    protected $accessorsAndMutatorsEnabled = true;
-
     public function getTableName()
     {
         return 'customvar';
@@ -60,16 +58,4 @@ class Customvar extends Model
 
         $relations->hasMany('customvar_flat', CustomvarFlat::class);
     }
-
-    protected function mutateValueProperty($json)
-    {
-        if (is_string($json)) {
-            $data = json_decode($json);
-            if ($data !== null) {
-                $json = $data;
-            }
-        }
-
-        return $json;
-    }
 }
diff --git a/library/Icingadb/Model/Host.php b/library/Icingadb/Model/Host.php
index 3ec25fa7..1030ab1d 100644
--- a/library/Icingadb/Model/Host.php
+++ b/library/Icingadb/Model/Host.php
@@ -8,8 +8,8 @@ use Icinga\Module\Icingadb\Common\Auth;
 use Icinga\Module\Icingadb\Model\Behavior\BoolCast;
 use Icinga\Module\Icingadb\Model\Behavior\ReRoute;
 use ipl\Orm\Behaviors;
+use ipl\Orm\Defaults;
 use ipl\Orm\Model;
-use ipl\Orm\Query;
 use ipl\Orm\Relations;
 use ipl\Orm\ResultSet;
 
@@ -20,8 +20,6 @@ class Host extends Model
 {
     use Auth;
 
-    protected $accessorsAndMutatorsEnabled = true;
-
     public function getTableName()
     {
         return 'host';
@@ -147,25 +145,20 @@ class Host extends Model
         ]));
     }
 
-    /**
-     * Mutates flattened custom vars to an associative array
-     *
-     * @param  Query|ResultSet $_
-     *
-     * @return array
-     */
-    public function mutateVarsProperty($_): array
+    public function createDefaults(Defaults $defaults)
     {
-        if (! $this->customvar_flat instanceof ResultSet) {
-            $this->applyRestrictions($this->customvar_flat);
-        }
+        $defaults->add('vars', function (self $subject) {
+            if (! $subject->customvar_flat instanceof ResultSet) {
+                $this->applyRestrictions($subject->customvar_flat);
+            }
 
-        $vars = [];
-        foreach ($this->customvar_flat as $customVar) {
-            $vars[$customVar->flatname] = $customVar->flatvalue;
-        }
+            $vars = [];
+            foreach ($subject->customvar_flat as $customVar) {
+                $vars[$customVar->flatname] = $customVar->flatvalue;
+            }
 
-        return $vars;
+            return $vars;
+        });
     }
 
     public function createRelations(Relations $relations)
diff --git a/library/Icingadb/Model/Service.php b/library/Icingadb/Model/Service.php
index cb5531c3..4ed7b806 100644
--- a/library/Icingadb/Model/Service.php
+++ b/library/Icingadb/Model/Service.php
@@ -8,8 +8,8 @@ use Icinga\Module\Icingadb\Common\Auth;
 use Icinga\Module\Icingadb\Model\Behavior\BoolCast;
 use Icinga\Module\Icingadb\Model\Behavior\ReRoute;
 use ipl\Orm\Behaviors;
+use ipl\Orm\Defaults;
 use ipl\Orm\Model;
-use ipl\Orm\Query;
 use ipl\Orm\Relations;
 use ipl\Orm\ResultSet;
 
@@ -17,8 +17,6 @@ class Service extends Model
 {
     use Auth;
 
-    protected $accessorsAndMutatorsEnabled = true;
-
     public function getTableName()
     {
         return 'service';
@@ -137,25 +135,20 @@ class Service extends Model
         ]));
     }
 
-    /**
-     * Mutates flattened custom vars to an associative array
-     *
-     * @param  Query|ResultSet $_
-     *
-     * @return array
-     */
-    public function mutateVarsProperty($_): array
+    public function createDefaults(Defaults $defaults)
     {
-        if (! $this->customvar_flat instanceof ResultSet) {
-            $this->applyRestrictions($this->customvar_flat);
-        }
+        $defaults->add('vars', function (self $subject) {
+            if (! $subject->customvar_flat instanceof ResultSet) {
+                $this->applyRestrictions($subject->customvar_flat);
+            }
 
-        $vars = [];
-        foreach ($this->customvar_flat as $customVar) {
-            $vars[$customVar->flatname] = $customVar->flatvalue;
-        }
+            $vars = [];
+            foreach ($subject->customvar_flat as $customVar) {
+                $vars[$customVar->flatname] = $customVar->flatvalue;
+            }
 
-        return $vars;
+            return $vars;
+        });
     }
 
     public function createRelations(Relations $relations)
diff --git a/test/php/library/Icingadb/Common/MacrosTest.php b/test/php/library/Icingadb/Common/MacrosTest.php
index c515c75f..dd01a01f 100644
--- a/test/php/library/Icingadb/Common/MacrosTest.php
+++ b/test/php/library/Icingadb/Common/MacrosTest.php
@@ -15,25 +15,25 @@ class MacrosTest extends TestCase
 {
     use Macros;
 
+    const VARS = [
+        'os'      => "Ubuntu",
+        'days[0]' => 'mo',
+        'days[1]' => 'tue',
+        'days[2]' => 'wed',
+        'days[3]' => 'thu',
+        'days[4]' => 'fr'
+    ];
+
     public function testHostMacros()
     {
         $mock = \Mockery::mock(Host::class);
         $mock->name = 'test';
         $mock->address = '1.1.1.1';
         $mock->address6 = '::1';
+        $mock->vars = self::VARS;
 
         $mock->hostgroup = new Query();
 
-        $mock->vars = null;
-        $mock->shouldReceive('mutateVarsProperty')->once()->andReturn([
-            'os'      => "Ubuntu",
-            'days[0]' => 'mo',
-            'days[1]' => 'tue',
-            'days[2]' => 'wed',
-            'days[3]' => 'thu',
-            'days[4]' => 'fr'
-        ]);
-
         $this->assertEquals($mock->name, $this->expandMacros('$host.name$', $mock));
         $this->assertEquals($mock->name, $this->expandMacros('$name$', $mock));
         $this->assertEquals($mock->address, $this->expandMacros('$host.address$', $mock));
@@ -64,33 +64,15 @@ class MacrosTest extends TestCase
         $mock = \Mockery::mock(Service::class);
         $mock->name = 'test-service';
         $mock->description = 'A test service';
+        $mock->vars = self::VARS;
 
         $mock->servicegroup = new Query();
 
-        $mock->vars = null;
-        $mock->shouldReceive('mutateVarsProperty')->once()->andReturn([
-            'os'      => "Ubuntu",
-            'days[0]' => 'mo',
-            'days[1]' => 'tue',
-            'days[2]' => 'wed',
-            'days[3]' => 'thu',
-            'days[4]' => 'fr'
-        ]);
-
         $hostMock = \Mockery::mock(Host::class);
         $hostMock->name = 'test';
         $hostMock->address = '1.1.1.1';
         $hostMock->hostgroup = new ResultSet(new \ArrayIterator());
-
-        $hostMock->vars = null;
-        $hostMock->shouldReceive('mutateVarsProperty')->once()->andReturn([
-            'os'      => "Ubuntu",
-            'days[0]' => 'mo',
-            'days[1]' => 'tue',
-            'days[2]' => 'wed',
-            'days[3]' => 'thu',
-            'days[4]' => 'fr'
-        ]);
+        $hostMock->vars = self::VARS;
 
         $mock->host = $hostMock;