diff --git a/src/core/tcp.c b/src/core/tcp.c
index dab3bd62..a3f8ea04 100644
--- a/src/core/tcp.c
+++ b/src/core/tcp.c
@@ -2,15 +2,6 @@
  * @file 
  * Transmission Control Protocol for IP
  * See also @ref tcp_raw
- *
- * @defgroup tcp_raw TCP
- * @ingroup callbackstyle_api
- * Transmission Control Protocol for IP\n
- * @see @ref raw_api and @ref netconn
- *
- * Common functions for the TCP implementation, such as functinos
- * for manipulating the data structures and the TCP timer functions. TCP functions
- * related to input and output is found in tcp_in.c and tcp_out.c respectively.\n
  */
 
 /*
@@ -45,6 +36,17 @@
  *
  */
 
+/**
+ * @defgroup tcp_raw TCP
+ * @ingroup raw_api
+ * Transmission Control Protocol for IP\n
+ * @see @ref raw_api and @ref netconn
+ *
+ * Common functions for the TCP implementation, such as functinos
+ * for manipulating the data structures and the TCP timer functions. TCP functions
+ * related to input and output is found in tcp_in.c and tcp_out.c respectively.\n
+ */
+
 #include "lwip/opt.h"
 
 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
@@ -1095,7 +1097,7 @@ tcp_slowtmr_start:
     if (pcb_remove) {
       struct tcp_pcb *pcb2;
 #if LWIP_CALLBACK_API
-      tcp_err_fn err_fn;
+      tcp_err_fn err_fn = pcb->errf;
 #endif /* LWIP_CALLBACK_API */
       void *err_arg;
       tcp_pcb_purge(pcb);
@@ -1114,9 +1116,6 @@ tcp_slowtmr_start:
                  pcb->local_port, pcb->remote_port);
       }
 
-#if LWIP_CALLBACK_API
-      err_fn = pcb->errf;
-#endif /* LWIP_CALLBACK_API */
       err_arg = pcb->callback_arg;
       pcb2 = pcb;
       pcb = pcb->next;
@@ -1681,7 +1680,6 @@ tcp_sent(struct tcp_pcb *pcb, tcp_sent_fn sent)
  * @ingroup tcp_raw
  * Used to specify the function that should be called when a fatal error
  * has occurred on the connection.
- * @note The corresponding pcb is already freed when this callback is called!
  *
  * @param pcb tcp_pcb to set the err callback
  * @param err callback function to call for this pcb when a fatal error
diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 7c936229..318514c2 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -1325,6 +1325,13 @@
 #if !defined(LWIP_EVENT_API) && !defined(LWIP_CALLBACK_API) || defined __DOXYGEN__
 #define LWIP_EVENT_API                  0
 #define LWIP_CALLBACK_API               1
+#else
+#ifndef LWIP_EVENT_API
+#define LWIP_EVENT_API                  0
+#endif
+#ifndef LWIP_CALLBACK_API
+#define LWIP_CALLBACK_API               0
+#endif
 #endif
 
 /**
@@ -1359,7 +1366,7 @@
  * Ethernet.
  */
 #if !defined PBUF_LINK_HLEN || defined __DOXYGEN__
-#if defined LWIP_HOOK_VLAN_SET
+#if defined LWIP_HOOK_VLAN_SET || defined __DOXYGEN__
 #define PBUF_LINK_HLEN                  (18 + ETH_PAD_SIZE)
 #else /* LWIP_HOOK_VLAN_SET */
 #define PBUF_LINK_HLEN                  (14 + ETH_PAD_SIZE)
diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index 0ae49a0f..35584b45 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -350,11 +350,13 @@ struct tcp_pcb * tcp_new     (void);
 struct tcp_pcb * tcp_new_ip_type (u8_t type);
 
 void             tcp_arg     (struct tcp_pcb *pcb, void *arg);
-void             tcp_accept  (struct tcp_pcb *pcb, tcp_accept_fn accept);
+#if LWIP_CALLBACK_API
 void             tcp_recv    (struct tcp_pcb *pcb, tcp_recv_fn recv);
 void             tcp_sent    (struct tcp_pcb *pcb, tcp_sent_fn sent);
-void             tcp_poll    (struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval);
 void             tcp_err     (struct tcp_pcb *pcb, tcp_err_fn err);
+void             tcp_accept  (struct tcp_pcb *pcb, tcp_accept_fn accept);
+#endif /* LWIP_CALLBACK_API */
+void             tcp_poll    (struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval);
 
 #define          tcp_mss(pcb)             (((pcb)->flags & TF_TIMESTAMP) ? ((pcb)->mss - 12)  : (pcb)->mss)
 #define          tcp_sndbuf(pcb)          (TCPWND16((pcb)->snd_buf))