diff --git a/src/core/ipv6/ip6_frag.c b/src/core/ipv6/ip6_frag.c
index d6f7ee1d..f33f4fb9 100644
--- a/src/core/ipv6/ip6_frag.c
+++ b/src/core/ipv6/ip6_frag.c
@@ -51,7 +51,7 @@
 
 #include <string.h>
 
-#if LWIP_IPV6_REASS  /* don't build if not configured for use in lwipopts.h */
+#if LWIP_IPV6 && LWIP_IPV6_REASS  /* don't build if not configured for use in lwipopts.h */
 
 
 /** Setting this to 0, you can turn off checking the fragments for overlapping
@@ -518,9 +518,9 @@ nullreturn:
   return NULL;
 }
 
-#endif /* LWIP_IPV6_REASS */
+#endif /* LWIP_IPV6 ^^ LWIP_IPV6_REASS */
 
-#if LWIP_IPV6_FRAG
+#if LWIP_IPV6 && LWIP_IPV6_FRAG
 
 /** Allocate a new struct pbuf_custom_ref */
 static struct pbuf_custom_ref*
@@ -686,4 +686,4 @@ ip6_frag(struct pbuf *p, struct netif *netif, ip6_addr_t *dest)
   return ERR_OK;
 }
 
-#endif /* LWIP_IPV6_FRAG */
+#endif /* LWIP_IPV6 && LWIP_IPV6_FRAG */
diff --git a/src/include/ipv6/lwip/dhcp6.h b/src/include/ipv6/lwip/dhcp6.h
index e116f5c7..83ce306b 100644
--- a/src/include/ipv6/lwip/dhcp6.h
+++ b/src/include/ipv6/lwip/dhcp6.h
@@ -50,7 +50,7 @@
 
 struct dhcp6
 {
-  TODO: implement DHCP6
+  //TODO: implement DHCP6
 };
 
 #endif /* LWIP_IPV6_DHCP6 */
diff --git a/src/include/ipv6/lwip/ip6_frag.h b/src/include/ipv6/lwip/ip6_frag.h
index 12294a97..75898b8f 100644
--- a/src/include/ipv6/lwip/ip6_frag.h
+++ b/src/include/ipv6/lwip/ip6_frag.h
@@ -51,7 +51,7 @@ extern "C" {
 #endif
 
 
-#if LWIP_IPV6_REASS  /* don't build if not configured for use in lwipopts.h */
+#if LWIP_IPV6 && LWIP_IPV6_REASS  /* don't build if not configured for use in lwipopts.h */
 
 /* The IPv6 reassembly timer interval in milliseconds. */
 #define IP6_REASS_TMR_INTERVAL 1000
@@ -73,9 +73,9 @@ struct ip6_reassdata {
 void ip6_reass_tmr(void);
 struct pbuf * ip6_reass(struct pbuf *p);
 
-#endif /* LWIP_IPV6_REASS */
+#endif /* LWIP_IPV6 && LWIP_IPV6_REASS */
 
-#if LWIP_IPV6_FRAG  /* don't build if not configured for use in lwipopts.h */
+#if LWIP_IPV6 && LWIP_IPV6_FRAG  /* don't build if not configured for use in lwipopts.h */
 
 /** A custom pbuf that holds a reference to another pbuf, which is freed
  * when this custom pbuf is freed. This is used to create a custom PBUF_REF
@@ -92,7 +92,7 @@ struct pbuf_custom_ref {
 
 err_t ip6_frag(struct pbuf *p, struct netif *netif, ip6_addr_t *dest);
 
-#endif /* LWIP_IPV6_FRAG */
+#endif /* LWIP_IPV6 && LWIP_IPV6_FRAG */
 
 
 #ifdef __cplusplus
diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index fdd12567..b37d5cf4 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -377,7 +377,7 @@ struct tcp_pcb * tcp_new_ip6 (void);
 #define          tcp_bind_ip6(pcb, ip6addr, port) \
                    tcp_bind(pcb, ip6_2_ip(ip6addr), port)
 #define          tcp_connect_ip6(pcb, ip6addr, port, connected) \
-                   udp_connect(pcb, ip6_2_ip(ip6addr), port, connected)
+                   tcp_connect(pcb, ip6_2_ip(ip6addr), port, connected)
 struct tcp_pcb * tcp_listen_dual_with_backlog(struct tcp_pcb *pcb, u8_t backlog);
 #define          tcp_listen_dual(pcb) tcp_listen_dual_with_backlog(pcb, TCP_DEFAULT_LISTEN_BACKLOG)
 #else /* LWIP_IPV6 */