diff --git a/collects/frtime/frp-core.ss b/collects/frtime/frp-core.ss
index 8c7741f73b..162b322923 100644
--- a/collects/frtime/frp-core.ss
+++ b/collects/frtime/frp-core.ss
@@ -23,7 +23,8 @@
   
   (define frtime-version "0.3b -- Tue Nov 9 13:39:45 2004")
   
-  
+  (define (compose-continuation-mark-sets s1 s2)
+    s2)