diff --git a/whalesong/repl-prototype/server.rkt b/whalesong/repl-prototype/server.rkt
index 6f7e66a..a1fbf5a 100644
--- a/whalesong/repl-prototype/server.rkt
+++ b/whalesong/repl-prototype/server.rkt
@@ -149,5 +149,5 @@
          #:once-each 
          [("-p" "--port") p "Port (default 8000)" 
           (current-port (string->number p))]))
-  (start-server #:port (current-port)))
+  (sync (start-server #:port (current-port))))