diff --git a/scheme/lib/pop3.scm b/scheme/lib/pop3.scm
index 32824fc..ff020d1 100644
--- a/scheme/lib/pop3.scm
+++ b/scheme/lib/pop3.scm
@@ -153,7 +153,7 @@
 ;; return number of messages and number of bytes waiting at the maildrop
 ;;: connection -> integer x integer
 (define (pop3-stat connection)
-  (pop3-check-transaction-state connection 'pop3-stat)
+  (pop3-check-transaction-state connection pop3-stat)
   (let* ((response (pop3-send-command connection "STAT"))
          (match (regexp-search (rx (posix-string "([0-9]+) ([0-9]+)")) response)))
     (values (string->number (match:substring match 1))
@@ -162,7 +162,7 @@
 ;; dump the message number MSGID to (current-output-port)
 ;;: connection x integer -> status
 (define (pop3-get connection msgid)
-  (pop3-check-transaction-state connection 'pop3-get)
+  (pop3-check-transaction-state connection pop3-get)
   (let ((status (pop3-send-command connection
 				   (build-command "RETR" (number->string msgid)))))
     (pop3-dump (socket:inport (pop3-connection-command-socket connection)))
@@ -170,7 +170,7 @@
 
 ;;: connection x integer -> status
 (define (pop3-headers connection msgid)
-  (pop3-check-transaction-state connection 'pop3-headers)
+  (pop3-check-transaction-state connection pop3-headers)
   (let ((status (pop3-send-command connection
 				   (build-command "TOP" (number->string msgid) "0"))))
     (pop3-dump (socket:inport (pop3-connection-command-socket connection)))
@@ -180,7 +180,7 @@
 ;; ain't in the RFC, but seems to be supported by several servers.
 ;;: connection -> integer
 (define (pop3-last connection)
-  (pop3-check-transaction-state connection 'pop3-last)
+  (pop3-check-transaction-state connection pop3-last)
   (let ((response (pop3-send-command connection "LAST")))
     (string->number (car ((infix-splitter) response)))))
 
@@ -189,19 +189,19 @@
 ;; can be undeleted using the RSET command.
 ;;: connection x integer -> status
 (define (pop3-delete connection msgid)
-  (pop3-check-transaction-state connection 'pop3-delete)
+  (pop3-check-transaction-state connection pop3-delete)
   (pop3-send-command connection (build-command "DELE" (number->string msgid))))
 
 
 ;; any messages which have been marked for deletion are unmarked
 ;;: connection -> status
 (define (pop3-reset connection)
-  (pop3-check-transaction-state connection 'pop3-reset)
+  (pop3-check-transaction-state connection pop3-reset)
   (pop3-send-command connection "RSET"))
 
 ;;: connection -> status
 (define (pop3-quit connection)
-  (pop3-check-transaction-state connection 'pop3-quit)
+  (pop3-check-transaction-state connection pop3-quit)
   (let ((status (pop3-send-command connection "QUIT")))
     (close-socket (pop3-connection-command-socket connection))
     status))
@@ -226,7 +226,7 @@
 
 (define (pop3-check-transaction-state connection caller)
   (if (not (eq? (pop3-connection-state connection) 'connected))
-      (call-error "not in transaction state" caller)))
+      (error "not in transaction state" caller)))
 
 (define (pop3-read-response connection)
   (let* ((sock (pop3-connection-command-socket connection))