diff --git a/src/include/netif/ppp/ppp_impl.h b/src/include/netif/ppp/ppp_impl.h
index c342778f..092e7141 100644
--- a/src/include/netif/ppp/ppp_impl.h
+++ b/src/include/netif/ppp/ppp_impl.h
@@ -254,6 +254,11 @@ extern int       maxoctets_timeout;  /* Timeout for check of octets limit */
 #define PPP_OCTETS_DIRECTION_MAXSESSION 4
 #endif
 
+/* Data input is only used by CCP and ECP, which are not supported at this time,
+ * remove this entry from struct protent to save some flash
+ */
+#define PPP_DATAINPUT (CCP_SUPPORT || ECP_SUPPORT)
+
 /*
  * The following struct gives the addresses of procedures to call
  * for a particular protocol.
@@ -280,11 +285,10 @@ struct protent {
 			  void (*printer) (void *, const char *, ...),
 			  void *arg);
 #endif /* PRINTPKT_SUPPORT */
-    /* FIXME: data input is only used by CCP, which is not supported at this time,
-     *        should we remove this entry and save some flash ?
-     */
+#if PPP_DATAINPUT
     /* Process a received data packet */
     void (*datainput) (ppp_pcb *pcb, u_char *pkt, int len);
+#endif /* PPP_DATAINPUT */
 #if PRINTPKT_SUPPORT
     const char *name;		/* Text name of protocol */
     const char *data_name;	/* Text name of corresponding data protocol */
diff --git a/src/netif/ppp/ccp.c b/src/netif/ppp/ccp.c
index ff7e546c..9fdb7b70 100644
--- a/src/netif/ppp/ccp.c
+++ b/src/netif/ppp/ccp.c
@@ -192,7 +192,9 @@ const struct protent ccp_protent = {
 #if PRINTPKT_SUPPORT
     ccp_printpkt,
 #endif /* PRINTPKT_SUPPORT */
+#if PPP_DATAINPUT
     ccp_datainput,
+#endif /* PPP_DATAINPUT */
 #if PRINTPKT_SUPPORT
     "CCP",
     "Compressed",
diff --git a/src/netif/ppp/chap-new.c b/src/netif/ppp/chap-new.c
index 4a4e910d..d72f717b 100644
--- a/src/netif/ppp/chap-new.c
+++ b/src/netif/ppp/chap-new.c
@@ -651,7 +651,9 @@ const struct protent chap_protent = {
 #if PRINTPKT_SUPPORT
 	chap_print_pkt,
 #endif /* PRINTPKT_SUPPORT */
+#if PPP_DATAINPUT
 	NULL,		/* datainput */
+#endif /* PPP_DATAINPUT */
 #if PRINTPKT_SUPPORT
 	"CHAP",		/* name */
 	NULL,		/* data_name */
diff --git a/src/netif/ppp/eap.c b/src/netif/ppp/eap.c
index a118c76e..2169be70 100644
--- a/src/netif/ppp/eap.c
+++ b/src/netif/ppp/eap.c
@@ -123,7 +123,9 @@ const struct protent eap_protent = {
 #if PRINTPKT_SUPPORT
 	eap_printpkt,		/* print a packet in readable form */
 #endif /* PRINTPKT_SUPPORT */
+#if PPP_DATAINPUT
 	NULL,			/* process a received data packet */
+#endif /* PPP_DATAINPUT */
 #if PRINTPKT_SUPPORT
 	"EAP",			/* text name of protocol */
 	NULL,			/* text name of corresponding data protocol */
diff --git a/src/netif/ppp/ecp.c b/src/netif/ppp/ecp.c
index fcc97e08..949e196a 100644
--- a/src/netif/ppp/ecp.c
+++ b/src/netif/ppp/ecp.c
@@ -111,7 +111,9 @@ const struct protent ecp_protent = {
 #if PRINTPKT_SUPPORT
     ecp_printpkt,
 #endif /* PRINTPKT_SUPPORT */
+#if PPP_DATAINPUT
     NULL, /* ecp_datainput, */
+#endif /* PPP_DATAINPUT */
 #if PRINTPKT_SUPPORT
     "ECP",
     "Encrypted",
diff --git a/src/netif/ppp/ipcp.c b/src/netif/ppp/ipcp.c
index f22346cc..14f2a27a 100644
--- a/src/netif/ppp/ipcp.c
+++ b/src/netif/ppp/ipcp.c
@@ -290,7 +290,9 @@ const struct protent ipcp_protent = {
 #if PRINTPKT_SUPPORT
     ipcp_printpkt,
 #endif /* PRINTPKT_SUPPORT */
+#if PPP_DATAINPUT
     NULL,
+#endif /* PPP_DATAINPUT */
 #if PRINTPKT_SUPPORT
     "IPCP",
     "IP",
diff --git a/src/netif/ppp/ipv6cp.c b/src/netif/ppp/ipv6cp.c
index 72470670..cfa1336e 100644
--- a/src/netif/ppp/ipv6cp.c
+++ b/src/netif/ppp/ipv6cp.c
@@ -283,7 +283,9 @@ const struct protent ipv6cp_protent = {
 #if PRINTPKT_SUPPORT
     ipv6cp_printpkt,
 #endif /* PRINTPKT_SUPPORT */
+#if PPP_DATAINPUT
     NULL,
+#endif /* PPP_DATAINPUT */
 #if PRINTPKT_SUPPORT
     "IPV6CP",
     "IPV6",
diff --git a/src/netif/ppp/lcp.c b/src/netif/ppp/lcp.c
index 042729c9..e302e4d6 100644
--- a/src/netif/ppp/lcp.c
+++ b/src/netif/ppp/lcp.c
@@ -284,7 +284,9 @@ const struct protent lcp_protent = {
 #if PRINTPKT_SUPPORT
     lcp_printpkt,
 #endif /* PRINTPKT_SUPPORT */
+#if PPP_DATAINPUT
     NULL,
+#endif /* PPP_DATAINPUT */
 #if PRINTPKT_SUPPORT
     "LCP",
     NULL,
diff --git a/src/netif/ppp/upap.c b/src/netif/ppp/upap.c
index efb6fc30..cdc9ce34 100644
--- a/src/netif/ppp/upap.c
+++ b/src/netif/ppp/upap.c
@@ -101,7 +101,9 @@ const struct protent pap_protent = {
 #if PRINTPKT_SUPPORT
     upap_printpkt,
 #endif /* PRINTPKT_SUPPORT */
+#if PPP_DATAINPUT
     NULL,
+#endif /* PPP_DATAINPUT */
 #if PRINTPKT_SUPPORT
     "PAP",
     NULL,