diff --git a/src/apps/mqtt/mqtt.c b/src/apps/mqtt/mqtt.c
index c46e76af..2efd85fa 100644
--- a/src/apps/mqtt/mqtt.c
+++ b/src/apps/mqtt/mqtt.c
@@ -1231,6 +1231,7 @@ mqtt_client_connect(mqtt_client_t *client, const ip_addr_t *ip_addr, u16_t port,
     }
     len = strlen(client_info->will_topic);
     LWIP_ERROR("mqtt_client_connect: client_info->will_topic length overflow", len <= 0xFF, return ERR_VAL);
+    LWIP_ERROR("mqtt_client_connect: client_info->will_topic length must be > 0", len > 0, return ERR_VAL);
     will_topic_len = (u8_t)len;
     len = strlen(client_info->will_msg);
     LWIP_ERROR("mqtt_client_connect: client_info->will_msg length overflow", len <= 0xFF, return ERR_VAL);