diff --git a/code/forms/SubsitesTreeDropdownField.php b/code/forms/SubsitesTreeDropdownField.php
index 287acb1c..523de47a 100644
--- a/code/forms/SubsitesTreeDropdownField.php
+++ b/code/forms/SubsitesTreeDropdownField.php
@@ -5,6 +5,7 @@
 use SilverStripe\Control\Controller;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Control\Session;
+use SilverStripe\Core\Manifest\ModuleLoader;
 use SilverStripe\Forms\TreeDropdownField;
 use SilverStripe\View\Requirements;
 
@@ -28,7 +29,8 @@ public function Field($properties = [])
     {
         $html = parent::Field($properties);
 
-        Requirements::javascript('subsites/javascript/SubsitesTreeDropdownField.js');
+        $module = ModuleLoader::getModule('silverstripe/subsites');
+        Requirements::javascript($module->getRelativeResourcePath('javascript/SubsitesTreeDropdownField.js'));
 
         return $html;
     }
diff --git a/code/pages/SubsitesVirtualPage.php b/code/pages/SubsitesVirtualPage.php
index e2a68ae1..541bf868 100644
--- a/code/pages/SubsitesVirtualPage.php
+++ b/code/pages/SubsitesVirtualPage.php
@@ -5,7 +5,6 @@
 use SilverStripe\CMS\Model\SiteTree;
 use SilverStripe\CMS\Model\VirtualPage;
 use SilverStripe\Control\Controller;
-use SilverStripe\Control\Session;
 use SilverStripe\Core\Config\Config;
 use SilverStripe\Forms\DropdownField;
 use SilverStripe\Forms\LabelField;
@@ -15,6 +14,7 @@
 use SilverStripe\ORM\DataObject;
 use SilverStripe\Subsites\Forms\SubsitesTreeDropdownField;
 use SilverStripe\Subsites\Model\Subsite;
+use SilverStripe\Subsites\State\SubsiteState;
 use SilverStripe\View\ArrayData;
 
 class SubsitesVirtualPage extends VirtualPage
@@ -139,7 +139,10 @@ public function fieldLabels($includerelations = true)
 
     public function getCopyContentFromID_SubsiteID()
     {
-        return $this->CopyContentFromID ? (int)$this->CopyContentFrom()->SubsiteID : (int)Session::get('SubsiteID');
+        if ($this->CopyContentFromID) {
+            return (int) $this->CopyContentFrom()->SubsiteID;
+        }
+        return SubsiteState::singleton()->getSubsiteId();
     }
 
     public function getVirtualFields()
@@ -177,22 +180,22 @@ public function onBeforeWrite()
         if ($this->CustomMetaTitle) {
             $this->MetaTitle = $this->CustomMetaTitle;
         } else {
-            $this->MetaTitle = $this->ContentSource()->MetaTitle ? $this->ContentSource()->MetaTitle : $this->MetaTitle;
+            $this->MetaTitle = $this->ContentSource()->MetaTitle ?: $this->MetaTitle;
         }
         if ($this->CustomMetaKeywords) {
             $this->MetaKeywords = $this->CustomMetaKeywords;
         } else {
-            $this->MetaKeywords = $this->ContentSource()->MetaKeywords ? $this->ContentSource()->MetaKeywords : $this->MetaKeywords;
+            $this->MetaKeywords = $this->ContentSource()->MetaKeywords ?: $this->MetaKeywords;
         }
         if ($this->CustomMetaDescription) {
             $this->MetaDescription = $this->CustomMetaDescription;
         } else {
-            $this->MetaDescription = $this->ContentSource()->MetaDescription ? $this->ContentSource()->MetaDescription : $this->MetaDescription;
+            $this->MetaDescription = $this->ContentSource()->MetaDescription ?: $this->MetaDescription;
         }
         if ($this->CustomExtraMeta) {
             $this->ExtraMeta = $this->CustomExtraMeta;
         } else {
-            $this->ExtraMeta = $this->ContentSource()->ExtraMeta ? $this->ContentSource()->ExtraMeta : $this->ExtraMeta;
+            $this->ExtraMeta = $this->ContentSource()->ExtraMeta ?: $this->ExtraMeta;
         }
     }
 
@@ -217,13 +220,13 @@ public function validURLSegment()
             $origDisableSubsiteFilter = Subsite::$disable_subsite_filter;
             Subsite::$disable_subsite_filter = true;
             $existingPage = DataObject::get_one(
-                'SilverStripe\\CMS\\Model\\SiteTree',
+                SiteTree::class,
                 "\"URLSegment\" = '$this->URLSegment' $IDFilter $parentFilter",
                 false // disable cache, it doesn't include subsite status in the key
             );
             Subsite::$disable_subsite_filter = $origDisableSubsiteFilter;
             $existingPageInSubsite = DataObject::get_one(
-                'SilverStripe\\CMS\\Model\\SiteTree',
+                SiteTree::class,
                 "\"URLSegment\" = '$this->URLSegment' $IDFilter $parentFilter",
                 false // disable cache, it doesn't include subsite status in the key
             );
diff --git a/tests/php/SiteTreeSubsitesTest.php b/tests/php/SiteTreeSubsitesTest.php
index 3fce8a9d..68fba2e4 100644
--- a/tests/php/SiteTreeSubsitesTest.php
+++ b/tests/php/SiteTreeSubsitesTest.php
@@ -154,8 +154,8 @@ public function testTwoPagesWithSameURLOnDifferentSubsites()
         $p2->write();
 
         // Check that the URLs weren't modified in our set-up
-        $this->assertEquals($p1->URLSegment, 'test-page');
-        $this->assertEquals($p2->URLSegment, 'test-page');
+        $this->assertEquals('test-page', $p1->URLSegment);
+        $this->assertEquals('test-page', $p2->URLSegment);
 
         // Check that if we switch between the different subsites, we receive the correct pages
         Subsite::changeSubsite($s1);
@@ -215,8 +215,8 @@ public function testCopyToSubsite()
 
         /** @var Subsite $otherSubsite */
         $otherSubsite = $this->objFromFixture(Subsite::class, 'subsite1');
-        $staffPage = $this->objFromFixture('Page', 'staff'); // nested page
-        $contactPage = $this->objFromFixture('Page', 'contact'); // top level page
+        $staffPage = $this->objFromFixture(Page::class, 'staff'); // nested page
+        $contactPage = $this->objFromFixture(Page::class, 'contact'); // top level page
 
         $staffPage2 = $staffPage->duplicateToSubsite($otherSubsite->ID);
         $contactPage2 = $contactPage->duplicateToSubsite($otherSubsite->ID);
@@ -270,7 +270,7 @@ public function testValidateURLSegment()
     {
         $this->logInWithPermission('ADMIN');
         // Saving existing page in the same subsite doesn't change urls
-        $mainHome = $this->objFromFixture('Page', 'home');
+        $mainHome = $this->objFromFixture(Page::class, 'home');
         $mainSubsiteID = $this->idFromFixture(Subsite::class, 'main');
         Subsite::changeSubsite($mainSubsiteID);
         $mainHome->Content = '<p>Some new content</p>';
diff --git a/tests/php/SubsitesVirtualPageTest.php b/tests/php/SubsitesVirtualPageTest.php
index ac34a974..786586d6 100644
--- a/tests/php/SubsitesVirtualPageTest.php
+++ b/tests/php/SubsitesVirtualPageTest.php
@@ -262,7 +262,7 @@ public function testSubsiteVirtualPageCanHaveSameUrlsegmentAsOtherSubsite()
         $subsite2 = $this->objFromFixture(Subsite::class, 'subsite2');
         Subsite::changeSubsite($subsite1->ID);
 
-        $subsite1Page = $this->objFromFixture('Page', 'subsite1_staff');
+        $subsite1Page = $this->objFromFixture(Page::class, 'subsite1_staff');
         $subsite1Page->URLSegment = 'staff';
         $subsite1Page->write();
 
@@ -271,9 +271,10 @@ public function testSubsiteVirtualPageCanHaveSameUrlsegmentAsOtherSubsite()
         $subsite1Vp->CopyContentFromID = $subsite1Page->ID;
         $subsite1Vp->SubsiteID = $subsite1->ID;
         $subsite1Vp->write();
+
         $this->assertNotEquals(
-            (string) $subsite1Vp->URLSegment,
-            (string) $subsite1Page->URLSegment,
+            $subsite1Vp->URLSegment,
+            $subsite1Page->URLSegment,
             "Doesn't allow explicit URLSegment overrides when already existing in same subsite"
         );