diff --git a/src/include/netif/ppp/pppapi.h b/src/include/netif/ppp/pppapi.h
index cc1f221d..8c136f53 100644
--- a/src/include/netif/ppp/pppapi.h
+++ b/src/include/netif/ppp/pppapi.h
@@ -47,7 +47,7 @@ extern "C" {
 struct pppapi_msg_msg {
   ppp_pcb *ppp;
   union {
-#if ESP_PPP
+#if ESP_PPP && PPP_AUTH_SUPPORT
     struct {
       u8_t authtype;
       const char *user;
@@ -111,7 +111,7 @@ struct pppapi_msg {
 
 /* API for application */
 err_t pppapi_set_default(ppp_pcb *pcb);
-#if ESP_PPP
+#if ESP_PPP && PPP_AUTH_SUPPORT
 void pppapi_set_auth(ppp_pcb *pcb, u8_t authtype, const char *user, const char *passwd);
 #endif
 #if PPP_NOTIFY_PHASE
diff --git a/src/netif/ppp/pppapi.c b/src/netif/ppp/pppapi.c
index 8608978c..1aeefaff 100644
--- a/src/netif/ppp/pppapi.c
+++ b/src/netif/ppp/pppapi.c
@@ -82,7 +82,7 @@ pppapi_set_default(ppp_pcb *pcb)
   return err;
 }
 
-#if ESP_PPP
+#if ESP_PPP && PPP_AUTH_SUPPORT
 /**
  * Call ppp_set_auth() inside the tcpip_thread context.
  */