diff --git a/lib/DAV/LockPlugin.php b/lib/DAV/LockPlugin.php
index 4fdcd751..09f72c77 100644
--- a/lib/DAV/LockPlugin.php
+++ b/lib/DAV/LockPlugin.php
@@ -139,7 +139,7 @@ public function customProperties(PropFind $propFind, INode $node) {
 				return null;
 			}
 
-			return $lock->getTimeout();
+			return $lock->getETA() === FileLock::ETA_INFINITE ? null : $lock->getTimeout();
 		});
 
 		$propFind->handle(Application::DAV_PROPERTY_LOCK_OWNER_DISPLAYNAME, function () use ($nodeId, $node) {
@@ -278,7 +278,7 @@ private function getLockProperties(?FileLock $lock, Node $file): array {
 			Application::DAV_PROPERTY_LOCK_OWNER_DISPLAYNAME => $lock ? $lock->getDisplayName() : null,
 			Application::DAV_PROPERTY_LOCK_EDITOR => $lock ? $lock->getOwner() : null,
 			Application::DAV_PROPERTY_LOCK_TIME => $lock ? $lock->getCreatedAt() : null,
-			Application::DAV_PROPERTY_LOCK_TIMEOUT => $lock ? $lock->getTimeout() : null,
+			Application::DAV_PROPERTY_LOCK_TIMEOUT => $lock && $lock->getETA() !== FileLock::ETA_INFINITE ? $lock->getTimeout() : null,
 			Application::DAV_PROPERTY_LOCK_TOKEN => $lock ? $lock->getToken() : null,
 		];
 	}
diff --git a/tests/Feature/LockFeatureTest.php b/tests/Feature/LockFeatureTest.php
index 0ce84474..c2e2b229 100644
--- a/tests/Feature/LockFeatureTest.php
+++ b/tests/Feature/LockFeatureTest.php
@@ -387,6 +387,21 @@ public function testExtendLock() {
 		$this->assertEquals($id, $locks[0]->getId());
 	}
 
+	/**
+	 * Default config (LOCK_TIMEOUT = -1) must produce ETA_INFINITE, not a negative timestamp.
+	 * Regression: getTimeout() returned -60 which clients interpreted as a past expiry.
+	 */
+	public function testDefaultInfiniteTimeoutProducesEtaInfinite() {
+		\OCP\Server::get(IConfig::class)->setAppValue(Application::APP_ID, ConfigService::LOCK_TIMEOUT, '-1');
+
+		$file = $this->loginAndGetUserFolder(self::TEST_USER1)->newFile('test-file', 'AAA');
+		$this->lockManager->lock(new LockContext($file, ILock::TYPE_USER, self::TEST_USER1));
+		$locks = $this->lockManager->getLocks($file->getId());
+
+		$this->assertCount(1, $locks);
+		$this->assertEquals(FileLock::ETA_INFINITE, $locks[0]->getEta());
+	}
+
 	/**
 	 * Regression test for https://github.com/nextcloud/files_lock/issues/130
 	 */