diff --git a/src/core/ipv6/nd6.c b/src/core/ipv6/nd6.c
index 689e132..298b0ea 100644
--- a/src/core/ipv6/nd6.c
+++ b/src/core/ipv6/nd6.c
@@ -46,6 +46,7 @@
 #if LWIP_IPV6  /* don't build if not configured for use in lwipopts.h */
 
 #include "lwip/nd6.h"
+#include "lwip/priv/nd6_priv.h"
 #include "lwip/prot/nd6.h"
 #include "lwip/prot/icmp6.h"
 #include "lwip/pbuf.h"
diff --git a/src/core/memp.c b/src/core/memp.c
index d3f10a9..3162449 100644
--- a/src/core/memp.c
+++ b/src/core/memp.c
@@ -71,7 +71,7 @@
 #include "netif/ppp/ppp_opts.h"
 #include "lwip/netdb.h"
 #include "lwip/dns.h"
-#include "lwip/nd6.h"
+#include "lwip/priv/nd6_priv.h"
 #include "lwip/ip6_frag.h"
 #include "lwip/mld6.h"
 
diff --git a/src/include/lwip/nd6.h b/src/include/lwip/nd6.h
index 69a059b..817dfb9 100644
--- a/src/include/lwip/nd6.h
+++ b/src/include/lwip/nd6.h
@@ -48,96 +48,18 @@
 
 #if LWIP_IPV6  /* don't build if not configured for use in lwipopts.h */
 
-#include "lwip/pbuf.h"
-#include "lwip/ip6.h"
 #include "lwip/ip6_addr.h"
-#include "lwip/netif.h"
-
+#include "lwip/err.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-/** Struct for tables. */
-struct nd6_neighbor_cache_entry {
-  ip6_addr_t next_hop_address;
-  struct netif *netif;
-  u8_t lladdr[NETIF_MAX_HWADDR_LEN];
-  /*u32_t pmtu;*/
-#if LWIP_ND6_QUEUEING
-  /** Pointer to queue of pending outgoing packets on this entry. */
-  struct nd6_q_entry *q;
-#else /* LWIP_ND6_QUEUEING */
-  /** Pointer to a single pending outgoing packet on this entry. */
-  struct pbuf *q;
-#endif /* LWIP_ND6_QUEUEING */
-  u8_t state;
-  u8_t isrouter;
-  union {
-    u32_t reachable_time; /* in ms since value may originate from network packet */
-    u32_t delay_time;     /* ticks (ND6_TMR_INTERVAL) */
-    u32_t probes_sent;
-    u32_t stale_time;     /* ticks (ND6_TMR_INTERVAL) */
-  } counter;
-};
-
-struct nd6_destination_cache_entry {
-  ip6_addr_t destination_addr;
-  ip6_addr_t next_hop_addr;
-  u16_t pmtu;
-  u32_t age;
-};
-
-struct nd6_prefix_list_entry {
-  ip6_addr_t prefix;
-  struct netif *netif;
-  u32_t invalidation_timer; /* in ms since value may originate from network packet */
-#if LWIP_IPV6_AUTOCONFIG
-  u8_t flags;
-#define ND6_PREFIX_AUTOCONFIG_AUTONOMOUS 0x01
-#define ND6_PREFIX_AUTOCONFIG_ADDRESS_GENERATED 0x02
-#define ND6_PREFIX_AUTOCONFIG_ADDRESS_DUPLICATE 0x04
-#endif /* LWIP_IPV6_AUTOCONFIG */
-};
-
-struct nd6_router_list_entry {
-  struct nd6_neighbor_cache_entry *neighbor_entry;
-  u32_t invalidation_timer; /* in ms since value may originate from network packet */
-  u8_t flags;
-};
-
-enum nd6_neighbor_cache_entry_state {
-  ND6_NO_ENTRY = 0,
-  ND6_INCOMPLETE,
-  ND6_REACHABLE,
-  ND6_STALE,
-  ND6_DELAY,
-  ND6_PROBE
-};
-
-#if LWIP_ND6_QUEUEING
-/** struct for queueing outgoing packets for unknown address
-  * defined here to be accessed by memp.h
-  */
-struct nd6_q_entry {
-  struct nd6_q_entry *next;
-  struct pbuf *p;
-};
-#endif /* LWIP_ND6_QUEUEING */
-
 /** 1 second period */
 #define ND6_TMR_INTERVAL 1000
 
-/* Router tables. */
-/* @todo make these static? and entries accessible through API? */
-extern struct nd6_neighbor_cache_entry neighbor_cache[];
-extern struct nd6_destination_cache_entry destination_cache[];
-extern struct nd6_prefix_list_entry prefix_list[];
-extern struct nd6_router_list_entry default_router_list[];
-
-/* Default values, can be updated by a RA message. */
-extern u32_t reachable_time;
-extern u32_t retrans_timer;
+struct pbuf;
+struct netif;
 
 void nd6_tmr(void);
 void nd6_input(struct pbuf *p, struct netif *inp);
diff --git a/src/include/lwip/prot/nd6.h b/src/include/lwip/prot/nd6.h
index eae3d28..7f46c53 100644
--- a/src/include/lwip/prot/nd6.h
+++ b/src/include/lwip/prot/nd6.h
@@ -39,6 +39,7 @@
 
 #include "lwip/arch.h"
 #include "lwip/ip6_addr.h"
+#include "lwip/prot/ip6.h"
 
 #ifdef __cplusplus
 extern "C" {