diff --git a/apps/files_external/lib/sftp.php b/apps/files_external/lib/sftp.php
index c6be3f96bab1e75e5c4290dc1733e76e86fb0015..f3605c3aa2d61cfa3c5f06955478607fc2e67d7f 100644
--- a/apps/files_external/lib/sftp.php
+++ b/apps/files_external/lib/sftp.php
@@ -239,7 +239,7 @@ class SFTP extends OC\Files\Storage\Common {
 
 	public function touch($path, $mtime=null) {
 		try {
-			if ($mtime != null) return false;
+			if (!is_null($mtime)) return false;
 			if (!$this->file_exists($path)) {
 				$this->client->put($this->abs_path($path), '');
 			} else {