diff --git a/crypto.h b/crypto.h
index 5354758..426d6f9 100644
--- a/crypto.h
+++ b/crypto.h
@@ -132,6 +132,10 @@ struct netq_t;
 
 /**
  * Set of user parameters used by the handshake.
+ *
+ * A copy of default_user_parameters (see dtls.c) are passed to the
+ * get_user_parameters callback provided in dtls_handler_t and may be
+ * adapted according the user's requirements.
  */
 typedef struct dtls_user_parameters_t {
   /**
diff --git a/dtls.c b/dtls.c
index fbab793..c617375 100644
--- a/dtls.c
+++ b/dtls.c
@@ -670,6 +670,11 @@ dtls_set_handshake_header(uint8 type,
   return buf;
 }
 
+/**
+ * A copy of default_user_parameters are passed to the get_user_parameters
+ * callback provided in dtls_handler_t and may be adapted according the user's
+ * requirements.
+ */
 static const dtls_user_parameters_t default_user_parameters = {
   .cipher_suites =
 #ifdef DTLS_DEFAULT_CIPHER_SUITES