diff --git a/scsh/scsh-interfaces.scm b/scsh/scsh-interfaces.scm
index ae9c694..025bc6c 100644
--- a/scsh/scsh-interfaces.scm
+++ b/scsh/scsh-interfaces.scm
@@ -977,6 +977,10 @@
 	  open-control-tty
 	  set-tty-process-group
 	  tty-process-group
+
+	  tty?
+	  tty-file-name
+	  control-tty-file-name
 	  )))
 
 (define-interface signal-handler-interface