diff --git a/main/manager.c b/main/manager.c
index d0898257106a8aa9d0291d0d850d1bdbd253d555..011ae103ef4a7cac3333aa627bc8854dbb26f60a 100644
--- a/main/manager.c
+++ b/main/manager.c
@@ -5127,7 +5127,7 @@ static int process_message(struct mansession *s, const struct message *m)
 			|| !strcasecmp(action, "Challenge"))) {
 		user = astman_get_header(m, "Username");
 
-		if (check_manager_session_inuse(user)) {
+		if (!ast_strlen_zero(user) && check_manager_session_inuse(user)) {
 			report_session_limit(s);
 			sleep(1);
 			mansession_lock(s);