diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c
index b0aa8c024c..7e5471f2a3 100644
--- a/channels/chan_iax2.c
+++ b/channels/chan_iax2.c
@@ -4769,7 +4769,7 @@ static int handle_call_token(struct ast_iax2_full_hdr *fh, struct iax_ies *ies,
 	/* ----- Case 3 ----- */
 	} else { /* calltokens are not supported for this client, how do we respond? */
 		if (calltoken_required(sin, ies->username, subclass)) {
-			ast_log(LOG_ERROR, "Call rejected, CallToken Support required. If unexpected, resolve by placing address %s in the calltokenignore list or setting user %s requirecalltoken=no\n", ast_inet_ntoa(sin->sin_addr), ies->username);
+			ast_log(LOG_ERROR, "Call rejected, CallToken Support required. If unexpected, resolve by placing address %s in the calltokenignore list or setting user %s requirecalltoken=no\n", ast_inet_ntoa(sin->sin_addr), S_OR(ies->username, "guest"));
 			goto reject;
 		}
 		return 0; /* calltoken is not required for this addr, so permit it. */