diff --git a/code/Controllers/CMSMain.php b/code/Controllers/CMSMain.php
index 8b7e6525..4178b7d2 100644
--- a/code/Controllers/CMSMain.php
+++ b/code/Controllers/CMSMain.php
@@ -80,6 +80,10 @@ use Translatable;
  */
 class CMSMain extends LeftAndMain implements CurrentPageIdentifier, PermissionProvider
 {
+    /**
+     * Unique ID for page icons CSS block
+     */
+    const PAGE_ICONS_ID = 'PageIcons';
 
     private static $url_segment = 'pages';
 
@@ -167,7 +171,7 @@ class CMSMain extends LeftAndMain implements CurrentPageIdentifier, PermissionPr
         Requirements::javascript('silverstripe/cms: client/dist/js/bundle.js');
         Requirements::javascript('silverstripe/cms: client/dist/js/SilverStripeNavigator.js');
         Requirements::css('silverstripe/cms: client/dist/styles/bundle.css');
-        Requirements::customCSS($this->generatePageIconsCss());
+        Requirements::customCSS($this->generatePageIconsCss(), self::PAGE_ICONS_ID);
 
         $module = ModuleLoader::getModule('silverstripe/cms');
         Requirements::add_i18n_javascript($module->getRelativeResourcePath('client/lang'), false, true);
diff --git a/code/Controllers/LeftAndMainPageIconsExtension.php b/code/Controllers/LeftAndMainPageIconsExtension.php
index 7044c2e3..aa95dc61 100644
--- a/code/Controllers/LeftAndMainPageIconsExtension.php
+++ b/code/Controllers/LeftAndMainPageIconsExtension.php
@@ -17,7 +17,7 @@ class LeftAndMainPageIconsExtension extends Extension
 
     public function init()
     {
-        Requirements::customCSS($this->generatePageIconsCss());
+        Requirements::customCSS($this->generatePageIconsCss(), CMSMain::PAGE_ICONS_ID);
     }
 
     /**