diff --git a/apps/httpserver_raw/httpd.c b/apps/httpserver_raw/httpd.c
index e567a3f..75dd76e 100644
--- a/apps/httpserver_raw/httpd.c
+++ b/apps/httpserver_raw/httpd.c
@@ -610,6 +610,9 @@ http_write(struct tcp_pcb *pcb, const void* ptr, u16_t *length, u8_t apiflags)
    err_t err;
    LWIP_ASSERT("length != NULL", length != NULL);
    len = *length;
+   if (len == 0) {
+     return ERR_OK;
+   }
    do {
      LWIP_DEBUGF(HTTPD_DEBUG | LWIP_DBG_TRACE, ("Trying go send %d bytes\n", len));
      err = tcp_write(pcb, ptr, len, apiflags);