diff --git a/src/Security/InheritedPermissionFlusher.php b/src/Security/InheritedPermissionFlusher.php
index fd5c257d1..bd784fa3b 100644
--- a/src/Security/InheritedPermissionFlusher.php
+++ b/src/Security/InheritedPermissionFlusher.php
@@ -42,6 +42,8 @@ class InheritedPermissionFlusher extends DataExtension implements Flushable
 
     /**
      * @param CacheFlusher[]
+     * @throws InvalidArgumentException
+     * @return $this
      */
     public function setServices($services)
     {
@@ -57,6 +59,8 @@ class InheritedPermissionFlusher extends DataExtension implements Flushable
         }
 
         $this->services = $services;
+
+        return $this;
     }
 
     /**
@@ -85,11 +89,7 @@ class InheritedPermissionFlusher extends DataExtension implements Flushable
      */
     protected function getMemberIDList()
     {
-        if (!$this->owner) {
-            return null;
-        }
-
-        if (!$this->owner->exists()) {
+        if (!$this->owner || !$this->owner->exists()) {
             return null;
         }
 
diff --git a/tests/php/Security/InheritedPermissionsFlusherTest.php b/tests/php/Security/InheritedPermissionsFlusherTest.php
index e940405b3..716234b72 100644
--- a/tests/php/Security/InheritedPermissionsFlusherTest.php
+++ b/tests/php/Security/InheritedPermissionsFlusherTest.php
@@ -16,7 +16,7 @@ class InheritedPermissionsFlusherTest extends SapphireTest
 {
     protected static $fixture_file = 'InheritedPermissionsFlusherTest.yml';
 
-    public function setUp()
+    protected function setUp()
     {
         parent::setUp();