diff --git a/private/self-signed-cert.rkt b/private/self-signed-cert.rkt
index d645afb..e261b74 100644
--- a/private/self-signed-cert.rkt
+++ b/private/self-signed-cert.rkt
@@ -212,8 +212,8 @@
 (version-define 1
    (BIO_get_mem_data (λ (bio-ptr)
                        (let ((r (BIO_ctrl bio-ptr BIO_CTRL_INFO 0)))
-                         (displayln r)
-                         (cadr r))))
+                         (let ((r* (subbytes (cadr r) 0 (car r))))
+                           r*))))
    (ASN1_OCTET_STRING_new (λ ()
                             (ASN1_STRING_type_new V_ASN1_OCTET_STRING)))
    )