diff -r b1e0fb71435d -r fdfe9b91d96e src/Pure/System/isabelle_system.scala
--- a/src/Pure/System/isabelle_system.scala	Tue Aug 29 12:04:13 2023 +0200
+++ b/src/Pure/System/isabelle_system.scala	Tue Aug 29 12:53:28 2023 +0200
@@ -481,7 +481,7 @@
             (entry, result)
           }
         for {
-          (entry, Some(res)) <- items
+          case (entry, Some(res)) <- items
           if !entry.isDirectory
           t <- Option(entry.getLastModifiedTime)
         } Files.setLastModifiedTime(res, t)