diff --git a/apps/files_trashbin/lib/Trashbin.php b/apps/files_trashbin/lib/Trashbin.php
index 99343dbe165..f72756e7aea 100644
--- a/apps/files_trashbin/lib/Trashbin.php
+++ b/apps/files_trashbin/lib/Trashbin.php
@@ -344,6 +344,8 @@ class Trashbin implements IEventListener {
 				$sizeDifference = $sourceInfo->getSize();
 				if ($sizeDifference < 0) {
 					$sizeDifference = null;
+				} else {
+					$sizeDifference = (int)$sizeDifference;
 				}
 				$trashStorage->getUpdater()->update($trashInternalPath, null, $sizeDifference);
 			}