diff --git a/apps/theming/css/default.css b/apps/theming/css/default.css
index fb541b7aca97f..bf7ad0f89ccf9 100644
--- a/apps/theming/css/default.css
+++ b/apps/theming/css/default.css
@@ -59,4 +59,10 @@
   --primary-invert-if-bright: no;
   --background-invert-if-dark: no;
   --background-invert-if-bright: invert(100%);
+  --image-logo: url('/core/img/logo/logo.png?v=0');
+  --image-logoheader: url('/core/img/logo/logo.png?v=0');
+  --image-favicon: url('/core/img/logo/logo.png?v=0');
+  --image-background-size: cover;
+  --image-background: url('/core/img/background.png?v=0');
+  --image-login-background: url('/core/img/background.png?v=0');
 }
diff --git a/apps/theming/lib/Themes/DefaultTheme.php b/apps/theming/lib/Themes/DefaultTheme.php
index df444ebe2d234..d327b7db6d4b9 100644
--- a/apps/theming/lib/Themes/DefaultTheme.php
+++ b/apps/theming/lib/Themes/DefaultTheme.php
@@ -191,7 +191,6 @@ public function getCSSVariables(): array {
 			'--background-invert-if-bright' => 'invert(100%)',
 		];
 
-		// Register image variables only if custom-defined
 		$backgroundDeleted = $this->config->getAppValue('theming', 'backgroundMime', '') === 'backgroundColor';
 		foreach(['logo', 'logoheader', 'favicon', 'background'] as $image) {
 			// If primary as background has been request, let's not define the background image
diff --git a/apps/theming/tests/ImageManagerTest.php b/apps/theming/tests/ImageManagerTest.php
index 6a9b77234bb74..0f22a774a3966 100644
--- a/apps/theming/tests/ImageManagerTest.php
+++ b/apps/theming/tests/ImageManagerTest.php
@@ -307,7 +307,7 @@ public function testCleanup() {
 		foreach ($folders as $index => $folder) {
 			$folder->expects($this->any())
 				->method('getName')
-				->willReturn($index);
+				->willReturn((string)$index);
 		}
 		$folders[0]->expects($this->once())->method('delete');
 		$folders[1]->expects($this->once())->method('delete');
diff --git a/apps/theming/tests/Themes/DefaultThemeTest.php b/apps/theming/tests/Themes/DefaultThemeTest.php
index 160efdba1426e..5086c5da8ee48 100644
--- a/apps/theming/tests/Themes/DefaultThemeTest.php
+++ b/apps/theming/tests/Themes/DefaultThemeTest.php
@@ -20,7 +20,7 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  *
  */
-namespace OCA\Theming\Tests\Service;
+namespace OCA\Theming\Tests;
 
 use OC\App\AppManager;
 use OCA\Theming\ImageManager;
@@ -68,6 +68,23 @@ protected function setUp(): void {
 			->method('getColorPrimary')
 			->willReturn('#0082c9');
 
+		$this->imageManager->expects($this->any())
+			->method('getImageUrl')
+			->willReturnCallback(function (string $name): string {
+				switch ($name) {
+					case 'logo':
+					case 'logoheader':
+					case 'favicon':
+						return '/core/img/logo/logo.png?v=0';
+					case 'background':
+					case 'login-background':
+						return '/core/img/background.png?v=0';
+					default:
+						return '';
+				}
+		});
+
+
 		$this->l10n
 			->expects($this->any())
 			->method('t')