diff -r 58576816d304 -r 25993910f212 src/Pure/Thy/sessions.scala
--- a/src/Pure/Thy/sessions.scala	Sat Mar 11 21:36:25 2023 +0100
+++ b/src/Pure/Thy/sessions.scala	Mon Mar 13 10:51:10 2023 +0100
@@ -1486,7 +1486,7 @@
         host = options.string("build_database_host"),
         port = options.int("build_database_port"),
         ssh =
-          options.proper_string("build_database_ssh_host").map(ssh_host =>
+          proper_string(options.string("build_database_ssh_host")).map(ssh_host =>
             SSH.open_session(options,
               host = ssh_host,
               user = options.string("build_database_ssh_user"),