diff --git a/contrib/basebackup_to_shell/basebackup_to_shell.c b/contrib/basebackup_to_shell/basebackup_to_shell.c
index f0ddef19870..fd462a8ff4d 100644
--- a/contrib/basebackup_to_shell/basebackup_to_shell.c
+++ b/contrib/basebackup_to_shell/basebackup_to_shell.c
@@ -86,6 +86,8 @@ _PG_init(void)
 							   0,
 							   NULL, NULL, NULL);
 
+	MarkGUCPrefixReserved("basebackup_to_shell");
+
 	BaseBackupAddTarget("shell", shell_check_detail, shell_get_sink);
 }