diff -r 6c1beb52d766 -r d961e11e0e87 src/Pure/Tools/update_comments.scala
--- a/src/Pure/Tools/update_comments.scala	Thu Sep 13 16:30:07 2018 +0200
+++ b/src/Pure/Tools/update_comments.scala	Thu Sep 13 21:18:43 2018 +0200
@@ -63,6 +63,6 @@
       for {
         spec <- specs
         file <- File.find_files(Path.explode(spec).file, file => file.getName.endsWith(".thy"))
-      } update_comments(Path.explode(File.standard_path(file)))
+      } update_comments(File.path(file))
     })
 }