diff --git a/tests/php/Controllers/CMSMainTest.php b/tests/php/Controllers/CMSMainTest.php
index e66cbc7b..4a0e71a3 100644
--- a/tests/php/Controllers/CMSMainTest.php
+++ b/tests/php/Controllers/CMSMainTest.php
@@ -287,7 +287,7 @@ class CMSMainTest extends FunctionalTest
         $this->assertEquals(403, $response->getStatusCode(), 'Add TopLevel page must fail for normal user');
 
         // with correct permissions
-        Security::setCurrentUser($rootEditUser);
+        $this->logInAs($rootEditUser);
         $response = $this->get('admin/pages/add');
 
         $response = $this->post(
@@ -307,8 +307,7 @@ class CMSMainTest extends FunctionalTest
         $location = $response->getHeader('X-ControllerURL');
         $this->assertNotEmpty($location, 'Must be a redirect on success');
         $this->assertContains('/show/', $location, 'Must redirect to /show/ the new page');
-        // TODO Logout
-        Security::setCurrentUser(null);
+        $this->logOut();
 
         $this->autoFollowRedirection = $origFollow;
     }
@@ -318,8 +317,7 @@ class CMSMainTest extends FunctionalTest
         $origFollow = $this->autoFollowRedirection;
         $this->autoFollowRedirection = false;
 
-        $adminUser = $this->objFromFixture(Member::class, 'admin');
-        Security::setCurrentUser($adminUser);
+        $this->logInAs('admin');
 
         // Create toplevel page
         $this->get('admin/pages/add');
@@ -393,8 +391,7 @@ class CMSMainTest extends FunctionalTest
     {
         $page3 = $this->objFromFixture(Page::class, 'page3');
         $page31 = $this->objFromFixture(Page::class, 'page31');
-        $adminuser = $this->objFromFixture(Member::class, 'admin');
-        Security::setCurrentUser($adminuser);
+        $this->logInAs('admin');
 
         $response = $this->get('admin/pages/edit/show/' . $page31->ID);
         $parser = new CSSContentParser($response->getBody());
diff --git a/tests/php/Model/SiteTreePermissionsTest.php b/tests/php/Model/SiteTreePermissionsTest.php
index 6db4b78d..ee436571 100644
--- a/tests/php/Model/SiteTreePermissionsTest.php
+++ b/tests/php/Model/SiteTreePermissionsTest.php
@@ -211,7 +211,7 @@ class SiteTreePermissionsTest extends FunctionalTest
             $page->canView(false),
             'Unauthenticated members cant view a page marked as "Viewable for any logged in users"'
         );
-        Security::setCurrentUser(null);
+        $this->logOut();
         $response = $this->get($page->RelativeLink());
         $this->assertEquals(
             $response->getStatusCode(),
@@ -225,14 +225,14 @@ class SiteTreePermissionsTest extends FunctionalTest
             $page->canView($websiteuser),
             'Authenticated members can view a page marked as "Viewable for any logged in users" even if they dont have access to the CMS'
         );
-        Security::setCurrentUser($websiteuser);
+        $this->logInAs($websiteuser);
         $response = $this->get($page->RelativeLink());
         $this->assertEquals(
             $response->getStatusCode(),
             200,
             'Authenticated members can view a page marked as "Viewable for any logged in users" even if they dont have access to the CMS'
         );
-        Security::setCurrentUser(null);
+        $this->logOut();
     }
 
     public function testRestrictedViewOnlyTheseUsers()
@@ -244,7 +244,7 @@ class SiteTreePermissionsTest extends FunctionalTest
             $page->canView(false),
             'Unauthenticated members cant view a page marked as "Viewable by these groups"'
         );
-        Security::setCurrentUser(null);
+        $this->logOut();
         $response = $this->get($page->RelativeLink());
         $this->assertEquals(
             $response->getStatusCode(),
@@ -258,14 +258,14 @@ class SiteTreePermissionsTest extends FunctionalTest
             $page->canView($subadminuser),
             'Authenticated members cant view a page marked as "Viewable by these groups" if theyre not in the listed groups'
         );
-        Security::setCurrentUser($subadminuser);
+        $this->LogInAs($subadminuser);
         $response = $this->get($page->RelativeLink());
         $this->assertEquals(
             $response->getStatusCode(),
             403,
             'Authenticated members cant view a page marked as "Viewable by these groups" if theyre not in the listed groups'
         );
-        Security::setCurrentUser(null);
+        $this->logOut();
 
         // website users
         $websiteuser = $this->objFromFixture(Member::class, 'websiteuser');
@@ -273,14 +273,14 @@ class SiteTreePermissionsTest extends FunctionalTest
             $page->canView($websiteuser),
             'Authenticated members can view a page marked as "Viewable by these groups" if theyre in the listed groups'
         );
-        Security::setCurrentUser($websiteuser);
+        $this->logInAs($websiteuser);
         $response = $this->get($page->RelativeLink());
         $this->assertEquals(
             $response->getStatusCode(),
             200,
             'Authenticated members can view a page marked as "Viewable by these groups" if theyre in the listed groups'
         );
-        Security::setCurrentUser(null);
+        $this->logOut();
     }
 
     public function testRestrictedEditLoggedInUsers()
@@ -344,7 +344,7 @@ class SiteTreePermissionsTest extends FunctionalTest
             $childPage->canView(false),
             'Unauthenticated members cant view a page marked as "Viewable by these groups" by inherited permission'
         );
-        Security::setCurrentUser(null);
+        $this->logOut();
         $response = $this->get($childPage->RelativeLink());
         $this->assertEquals(
             $response->getStatusCode(),
@@ -358,14 +358,14 @@ class SiteTreePermissionsTest extends FunctionalTest
             $childPage->canView($subadminuser),
             'Authenticated members can view a page marked as "Viewable by these groups" if theyre in the listed groups by inherited permission'
         );
-        Security::setCurrentUser($subadminuser);
+        $this->logInAs($subadminuser);
         $response = $this->get($childPage->RelativeLink());
         $this->assertEquals(
             $response->getStatusCode(),
             200,
             'Authenticated members can view a page marked as "Viewable by these groups" if theyre in the listed groups by inherited permission'
         );
-        Security::setCurrentUser(null);
+        $this->logOut();
     }
 
     public function testRestrictedEditInheritance()