diff --git a/scheme/lib/pop3.scm b/scheme/lib/pop3.scm
index fcadb78..059f278 100644
--- a/scheme/lib/pop3.scm
+++ b/scheme/lib/pop3.scm
@@ -218,7 +218,7 @@
 
 (define-record-type pop3-connection :pop3-connection
   (make-pop3-connection host-name command-socket log-port login password challenge state)
-  pop3-connection
+  pop3-connection?
   (host-name pop3-connection-host-name)
   (command-socket pop3-connection-command-socket)
   (log-port pop3-connection-log-port)