diff -ruN rfc3339.orig/rfc3339.scm rfc3339/rfc3339.scm
--- rfc3339.orig/rfc3339.scm	2024-09-30 01:13:50.935955075 +0200
+++ rfc3339/rfc3339.scm	2024-09-30 01:15:12.210602144 +0200
@@ -156,8 +156,9 @@
                          (c2 hh) ":" (c2 mm) ":" (c2 ss)
                          (cf fs) (tzstr tzoff)))))
 
-(define-record-printer (rfc3339 x out)
-  (fprintf out "#<rfc3339 ~s>" (rfc3339->string x)))
+(set-record-printer!
+ rfc3339 (lambda (x out)
+           (fprintf out "#<rfc3339 ~s>" (rfc3339->string x))))
 
 ;;; convenience functions