diff --git a/td/telegram/ContactsManager.cpp b/td/telegram/ContactsManager.cpp
index c2072e3f..ed2b4abd 100644
--- a/td/telegram/ContactsManager.cpp
+++ b/td/telegram/ContactsManager.cpp
@@ -48,6 +48,7 @@
 #include "td/utils/StringBuilder.h"
 #include "td/utils/Time.h"
 #include "td/utils/tl_helpers.h"
+#include "td/utils/utf8.h"
 
 #include <algorithm>
 #include <limits>
@@ -5359,6 +5360,19 @@ void ContactsManager::on_load_user_from_database(UserId user_id, string value) {
 
       log_event_parse(*u, value).ensure();
 
+      if (!check_utf8(u->first_name)) {
+        LOG(ERROR) << "Have invalid " << user_id << " first name \"" << u->first_name << '"';
+        u->first_name.clear();
+      }
+      if (!check_utf8(u->last_name)) {
+        LOG(ERROR) << "Have invalid " << user_id << " last name \"" << u->last_name << '"';
+        u->last_name.clear();
+      }
+      if (!check_utf8(u->username)) {
+        LOG(ERROR) << "Have invalid " << user_id << " username \"" << u->username << '"';
+        u->username.clear();
+      }
+
       u->is_saved = true;
       u->is_status_saved = true;
       update_user(u, user_id, true, true);