diff --git a/indenting2.el b/indenting2.el
index 6f42fef..3f06b30 100644
--- a/indenting2.el
+++ b/indenting2.el
@@ -1,6 +1,7 @@
 ;; Emacs indent settings
 (progn
   (mapcar #'(lambda (x) (put x 'scheme-indent-function 1))
-	  '(transition extend-transition prefix-transition))
+	  '(transition extend-transition prefix-transition
+		       extend-transition* prefix-transition*))
   (mapcar #'(lambda (x) (put x 'scheme-indent-function 2))
 	  '(role role/fresh yield)))
diff --git a/os2.rkt b/os2.rkt
index 1e138a0..a1de988 100644
--- a/os2.rkt
+++ b/os2.rkt
@@ -21,7 +21,9 @@
 	 (except-out (struct-out transition) transition)
 	 (rename-out [make-transition transition])
 	 extend-transition
+	 extend-transition*
 	 prefix-transition
+	 prefix-transition*
 
 	 role
 	 role/fresh
@@ -213,11 +215,25 @@
     [(transition state actions) (transition state (list actions more-actions))]
     [state (transition state more-actions)]))
 
+(define (extend-transition* t fn)
+  (match t
+    [(transition state actions)
+     (prefix-transition (fn state) actions)]
+    [state
+     (fn state)]))
+
 (define (prefix-transition t . more-actions)
   (match t
     [(transition state actions) (transition state (list more-actions actions))]
     [state (transition state more-actions)]))
 
+(define (prefix-transition* t fn)
+  (match t
+    [(transition state actions)
+     (extend-transition (fn state) actions)]
+    [state
+     (fn state)]))
+
 ;;---------------------------------------------------------------------------
 ;; Topics and roles