diff --git a/src/include/netif/ppp/ppp.h b/src/include/netif/ppp/ppp.h
index 718aa43b..ca4a4b81 100644
--- a/src/include/netif/ppp/ppp.h
+++ b/src/include/netif/ppp/ppp.h
@@ -42,7 +42,6 @@
 #include "lwip/mem.h"
 #include "lwip/netif.h"
 #include "lwip/sys.h"
-#include "lwip/sio.h"
 #include "lwip/timers.h"
 #if PPP_IPV6_SUPPORT
 #include "lwip/ip6_addr.h"
diff --git a/src/include/netif/ppp/pppos.h b/src/include/netif/ppp/pppos.h
index c18995c6..d924a9fc 100644
--- a/src/include/netif/ppp/pppos.h
+++ b/src/include/netif/ppp/pppos.h
@@ -38,7 +38,6 @@
 #define PPPOS_H
 
 #include "lwip/sys.h"
-#include "lwip/sio.h"
 
 #include "ppp.h"
 #include "vj.h"
diff --git a/src/netif/ppp/ppp.c b/src/netif/ppp/ppp.c
index 480bbccb..633a686d 100644
--- a/src/netif/ppp/ppp.c
+++ b/src/netif/ppp/ppp.c
@@ -88,7 +88,6 @@
 #include "lwip/tcpip.h"
 #include "lwip/api.h"
 #include "lwip/snmp.h"
-#include "lwip/sio.h"
 #include "lwip/sys.h"
 #include "lwip/ip4.h" /* for ip4_input() */
 #if PPP_IPV6_SUPPORT