diff --git a/conversation.rkt b/conversation.rkt
index 9fa7dc8..355d5d3 100644
--- a/conversation.rkt
+++ b/conversation.rkt
@@ -22,6 +22,10 @@
 
 	 ;; Generic utility messages
 	 (struct-out credit)
+
+	 (struct-out rpc-request)
+	 (struct-out rpc-reply)
+	 (struct-out rpc-error)
 	 )
 
 (struct arrived (who) #:prefab) ;; someone arrived
@@ -30,6 +34,10 @@
 
 (struct credit (who amount) #:prefab) ;; give someone an amount of credit
 
+(struct rpc-request (reply-to id body) #:prefab)
+(struct rpc-reply (id body) #:prefab)
+(struct rpc-error (id reason) #:prefab)
+
 (struct room (name ch))
 
 (struct room-state (name ch members) #:transparent)