diff --git a/scheme/httpd/surflets/surflet-handler.scm b/scheme/httpd/surflets/surflet-handler.scm
index 2b3eb97..389580f 100644
--- a/scheme/httpd/surflets/surflet-handler.scm
+++ b/scheme/httpd/surflets/surflet-handler.scm
@@ -433,10 +433,8 @@
 (define (set-session-data! new-data)
   (let ((session (session-lookup (instance-session-id))))
     (if session
-	(begin
-	  (set-session-session-data! session new-data)
-	  #t)
-	#f)))
+	(set-session-session-data! session new-data)
+	(error "Instance no longer alive."))))
 
 (define (get-session-data)
   (let ((session (session-lookup (instance-session-id))))