diff --git a/include/openthread/error.h b/include/openthread/error.h
index 497041893..7394b3134 100644
--- a/include/openthread/error.h
+++ b/include/openthread/error.h
@@ -67,12 +67,12 @@ extern "C" {
  * @defgroup api-dns   DNSv6
  * @defgroup api-icmp6 ICMPv6
  * @defgroup api-ip6   IPv6
- * @defgroup api-udp-group UDP
+ * @defgroup api-udp-group   UDP
  *
  * @{
  *
- * @defgroup api-udp       UDP
- * @defgroup api-udp-proxy UDP Proxy
+ * @defgroup api-udp         UDP
+ * @defgroup api-udp-forward UDP Forward
  *
  * @}
  *
@@ -128,6 +128,7 @@ extern "C" {
  * @defgroup api-logging             Logging
  * @defgroup api-ncp                 Network Co-Processor
  * @defgroup api-network-time        Network Time Synchronization
+ * @defgroup api-sntp                SNTP
  *
  * @}
  *