diff --git a/apps/files_external/lib/Lib/Storage/FTP.php b/apps/files_external/lib/Lib/Storage/FTP.php
index ae02f37b5754b..727d4c3707bae 100644
--- a/apps/files_external/lib/Lib/Storage/FTP.php
+++ b/apps/files_external/lib/Lib/Storage/FTP.php
@@ -123,7 +123,8 @@ public function filemtime($path) {
 					return $item['type'] === 'cdir';
 				}));
 				if ($currentDir) {
-					$time = \DateTime::createFromFormat('YmdHis', $currentDir['modify'] ?? '');
+					[$modify] = explode('.', $currentDir['modify'] ?? '');
+					$time = \DateTime::createFromFormat('YmdHis', $modify);
 					if ($time === false) {
 						throw new \Exception("Invalid date format for directory: $currentDir");
 					}
@@ -355,7 +356,10 @@ public function getDirectoryContent($directory): \Traversable {
 
 			$data = [];
 			$data['mimetype'] = $isDir ? FileInfo::MIMETYPE_FOLDER : $mimeTypeDetector->detectPath($name);
-			$data['mtime'] = \DateTime::createFromFormat('YmdGis', $file['modify'])->getTimestamp();
+
+			// strip fractional seconds
+			[$modify] = explode('.', $file['modify']);
+			$data['mtime'] = \DateTime::createFromFormat('YmdGis', $modify)->getTimestamp();
 			if ($data['mtime'] === false) {
 				$data['mtime'] = time();
 			}
diff --git a/apps/files_external/lib/Lib/Storage/FtpConnection.php b/apps/files_external/lib/Lib/Storage/FtpConnection.php
index c6f9a5c91b02b..327d0c48b5b47 100644
--- a/apps/files_external/lib/Lib/Storage/FtpConnection.php
+++ b/apps/files_external/lib/Lib/Storage/FtpConnection.php
@@ -90,7 +90,13 @@ public function rename(string $source, string $target) {
 	}
 
 	public function mdtm(string $path) {
-		return @ftp_mdtm($this->connection, $path);
+		$result = @ftp_mdtm($this->connection, $path);
+
+		// filezilla doesn't like empty path with mdtm
+		if ($result === -1 && $path === "") {
+			$result = @ftp_mdtm($this->connection, "/");
+		}
+		return $result;
 	}
 
 	public function size(string $path) {