diff --git a/src/netif/ppp/eui64.c b/src/netif/ppp/eui64.c
index d025eff4..aeeaa1a3 100644
--- a/src/netif/ppp/eui64.c
+++ b/src/netif/ppp/eui64.c
@@ -35,19 +35,16 @@
  * $Id: eui64.c,v 1.6 2002/12/04 23:03:32 paulus Exp $
  */
 
-#define RCSID	"$Id: eui64.c,v 1.6 2002/12/04 23:03:32 paulus Exp $"
+#include "lwip/opt.h"
+#if PPP_SUPPORT && PPP_IPV6_SUPPORT  /* don't build if not configured for use in lwipopts.h */
 
-#include "pppd.h"
-
-static const char rcsid[] = RCSID;
+#include "ppp_impl.h"
+#include "eui64.h"
 
 /*
  * eui64_ntoa - Make an ascii representation of an interface identifier
  */
-char *
-eui64_ntoa(e)
-    eui64_t e;
-{
+char *eui64_ntoa(eui64_t e) {
     static char buf[32];
 
     snprintf(buf, 32, "%02x%02x:%02x%02x:%02x%02x:%02x%02x",
@@ -55,3 +52,5 @@ eui64_ntoa(e)
 	     e.e8[4], e.e8[5], e.e8[6], e.e8[7]);
     return buf;
 }
+
+#endif /* PPP_SUPPORT && PPP_IPV6_SUPPORT */
diff --git a/src/netif/ppp/eui64.h b/src/netif/ppp/eui64.h
index 0f6b6fd4..8d735340 100644
--- a/src/netif/ppp/eui64.h
+++ b/src/netif/ppp/eui64.h
@@ -35,30 +35,12 @@
  * $Id: eui64.h,v 1.6 2002/12/04 23:03:32 paulus Exp $
 */
 
+#include "lwip/opt.h"
+#if PPP_SUPPORT && PPP_IPV6_SUPPORT  /* don't build if not configured for use in lwipopts.h */
+
 #ifndef __EUI64_H__
 #define __EUI64_H__
 
-#if !defined(INET6)
-#error	"this file should only be included when INET6 is defined"
-#endif /* not defined(INET6) */
-
-#if defined(SOL2)
-#include <netinet/in.h>
-
-typedef union {
-    uint8_t	e8[8];		/* lower 64-bit IPv6 address */
-    uint32_t	e32[2];		/* lower 64-bit IPv6 address */
-} eui64_t;
-
-/*
- * Declare the two below, since in.h only defines them when _KERNEL
- * is declared - which shouldn't be true when dealing with user-land programs
- */
-#define	s6_addr8	_S6_un._S6_u8
-#define	s6_addr32	_S6_un._S6_u32
-
-#else /* else if not defined(SOL2) */
-
 /*
  * TODO:
  *
@@ -71,8 +53,6 @@ typedef union
     u_int32_t e32[2];
 } eui64_t;
 
-#endif /* defined(SOL2) */
-
 #define eui64_iszero(e)		(((e).e32[0] | (e).e32[1]) == 0)
 #define eui64_equals(e, o)	(((e).e32[0] == (o).e32[0]) && \
 				((e).e32[1] == (o).e32[1]))
@@ -111,4 +91,4 @@ typedef union
 char *eui64_ntoa __P((eui64_t));	/* Returns ascii representation of id */
 
 #endif /* __EUI64_H__ */
-
+#endif /* PPP_SUPPORT && PPP_IPV6_SUPPORT */