diff --git a/apps/dav/lib/Connector/Sabre/MaintenancePlugin.php b/apps/dav/lib/Connector/Sabre/MaintenancePlugin.php
index e5db244c21..033bf4d1c0 100644
--- a/apps/dav/lib/Connector/Sabre/MaintenancePlugin.php
+++ b/apps/dav/lib/Connector/Sabre/MaintenancePlugin.php
@@ -82,7 +82,7 @@ class MaintenancePlugin extends ServerPlugin {
 	 */
 	public function checkMaintenanceMode() {
 		if ($this->config->getSystemValueBool('maintenance')) {
-			throw new ServiceUnavailable($this->l10n->t('System in maintenance mode.'));
+			throw new ServiceUnavailable($this->l10n->t('System is in maintenance mode.'));
 		}
 		if (Util::needUpgrade()) {
 			throw new ServiceUnavailable($this->l10n->t('Upgrade needed'));
diff --git a/apps/dav/tests/unit/Connector/Sabre/MaintenancePluginTest.php b/apps/dav/tests/unit/Connector/Sabre/MaintenancePluginTest.php
index 94bd1bb0b3..afef4e9141 100644
--- a/apps/dav/tests/unit/Connector/Sabre/MaintenancePluginTest.php
+++ b/apps/dav/tests/unit/Connector/Sabre/MaintenancePluginTest.php
@@ -55,7 +55,7 @@ class MaintenancePluginTest extends TestCase {
 
 	public function testMaintenanceMode() {
 		$this->expectException(\Sabre\DAV\Exception\ServiceUnavailable::class);
-		$this->expectExceptionMessage('System in maintenance mode.');
+		$this->expectExceptionMessage('System is in maintenance mode.');
 
 		$this->config
 			->expects($this->exactly(1))