diff --git a/lib/private/Files/ObjectStore/ObjectStoreStorage.php b/lib/private/Files/ObjectStore/ObjectStoreStorage.php
index 0963ffbb28f6b..78eb52a53d935 100644
--- a/lib/private/Files/ObjectStore/ObjectStoreStorage.php
+++ b/lib/private/Files/ObjectStore/ObjectStoreStorage.php
@@ -457,6 +457,14 @@ public function file_put_contents(string $path, mixed $data): int {
 	}
 
 	public function writeStream(string $path, $stream, ?int $size = null): int {
+		if ($size === null) {
+			$stats = fstat($stream);
+			if (is_array($stats) && isset($stats['size'])) {
+				$size = $stats['size'];
+				$this->logger->warning("stream size $size");
+			}
+		}
+
 		$stat = $this->stat($path);
 		if (empty($stat)) {
 			// create new file