diff --git a/src/apps/mqtt/mqtt.c b/src/apps/mqtt/mqtt.c
index 3dc6fb01..6c10bc05 100644
--- a/src/apps/mqtt/mqtt.c
+++ b/src/apps/mqtt/mqtt.c
@@ -1289,7 +1289,7 @@ mqtt_client_connect(mqtt_client_t *client, const ip_addr_t *ip_addr, u16_t port,
   /* Length is the sum of 2+"MQTT", protocol level, flags and keep alive */
   u16_t remaining_length = 2 + 4 + 1 + 1 + 2;
   u8_t flags = 0, will_topic_len = 0, will_msg_len = 0;
-  u8_t client_user_len = 0, client_pass_len = 0;
+  u16_t client_user_len = 0, client_pass_len = 0;
 
   LWIP_ASSERT_CORE_LOCKED();
   LWIP_ASSERT("mqtt_client_connect: client != NULL", client != NULL);
@@ -1330,9 +1330,9 @@ mqtt_client_connect(mqtt_client_t *client, const ip_addr_t *ip_addr, u16_t port,
   if (client_info->client_user != NULL) {
     flags |= MQTT_CONNECT_FLAG_USERNAME;
     len = strlen(client_info->client_user);
-    LWIP_ERROR("mqtt_client_connect: client_info->client_user length overflow", len <= 0xFF, return ERR_VAL);
+    LWIP_ERROR("mqtt_client_connect: client_info->client_user length overflow", len <= 0xFFFF, return ERR_VAL);
     LWIP_ERROR("mqtt_client_connect: client_info->client_user length must be > 0", len > 0, return ERR_VAL);
-    client_user_len = (u8_t)len;
+    client_user_len = (u16_t)len;
     len = remaining_length + 2 + client_user_len;
     LWIP_ERROR("mqtt_client_connect: remaining_length overflow", len <= 0xFFFF, return ERR_VAL);
     remaining_length = (u16_t)len;
@@ -1340,9 +1340,9 @@ mqtt_client_connect(mqtt_client_t *client, const ip_addr_t *ip_addr, u16_t port,
   if (client_info->client_pass != NULL) {
     flags |= MQTT_CONNECT_FLAG_PASSWORD;
     len = strlen(client_info->client_pass);
-    LWIP_ERROR("mqtt_client_connect: client_info->client_pass length overflow", len <= 0xFF, return ERR_VAL);
+    LWIP_ERROR("mqtt_client_connect: client_info->client_pass length overflow", len <= 0xFFFF, return ERR_VAL);
     LWIP_ERROR("mqtt_client_connect: client_info->client_pass length must be > 0", len > 0, return ERR_VAL);
-    client_pass_len = (u8_t)len;
+    client_pass_len = (u16_t)len;
     len = remaining_length + 2 + client_pass_len;
     LWIP_ERROR("mqtt_client_connect: remaining_length overflow", len <= 0xFFFF, return ERR_VAL);
     remaining_length = (u16_t)len;