diff --git a/middleware/envcheckmiddleware.php b/middleware/envcheckmiddleware.php
index 8c9ee37525..c2385c27b2 100644
--- a/middleware/envcheckmiddleware.php
+++ b/middleware/envcheckmiddleware.php
@@ -267,7 +267,7 @@ private function checkPassword($share, $password) {
 		$newHash = '';
 		if ($this->shareManager->checkPassword($share, $password)) {
 			// Save item id in session for future requests
-			$this->session->set('public_link_authenticated', $share->getId());
+			$this->session->set('public_link_authenticated', (string)$share->getId());
 			// @codeCoverageIgnoreStart
 			if (!empty($newHash)) {
 				// For future use
@@ -289,7 +289,7 @@ private function checkPassword($share, $password) {
 	private function checkSession($share) {
 		// Not authenticated ?
 		if (!$this->session->exists('public_link_authenticated')
-			|| $this->session->get('public_link_authenticated') !== $share->getId()
+			|| $this->session->get('public_link_authenticated') !== (string)$share->getId()
 		) {
 			throw new CheckException("Missing password", Http::STATUS_UNAUTHORIZED);
 		}
diff --git a/tests/unit/middleware/EnvCheckMiddlewareTest.php b/tests/unit/middleware/EnvCheckMiddlewareTest.php
index c744c492f5..aaef19225c 100644
--- a/tests/unit/middleware/EnvCheckMiddlewareTest.php
+++ b/tests/unit/middleware/EnvCheckMiddlewareTest.php
@@ -214,8 +214,8 @@ public function testBeforeControllerWithGuestNotation() {
 	public function testCheckSessionAfterPasswordEntry() {
 		$share = $this->mockShare('file', 'tester', 'image.png');
 
-		$this->mockSessionExists($share->getId());
-		$this->mockSessionWithShareId($share->getId());
+		$this->mockSessionExists((string)$share->getId());
+		$this->mockSessionWithShareId((string)$share->getId());
 
 		parent::invokePrivate($this->middleware, 'checkSession', [$share]);
 	}
@@ -365,8 +365,8 @@ public function testCheckAuthorisationWithNoPassword() {
 			Constants::PERMISSION_READ, $wrongPassword
 		);
 
-		$this->mockSessionExists($share->getId());
-		$this->mockSessionWithShareId($share->getId());
+		$this->mockSessionExists((string)$share->getId());
+		$this->mockSessionWithShareId((string)$share->getId());
 		parent::invokePrivate($this->middleware, 'checkAuthorisation', [$share, $password]);
 	}