diff --git a/src/api/api_lib.c b/src/api/api_lib.c
index e6a66468..33bfbc14 100644
--- a/src/api/api_lib.c
+++ b/src/api/api_lib.c
@@ -49,6 +49,7 @@
 #include "lwip/ip.h"
 #include "lwip/raw.h"
 #include "lwip/udp.h"
+#include "lwip/priv/api_msg.h"
 #include "lwip/priv/tcp_priv.h"
 #include "lwip/priv/tcpip_priv.h"
 
@@ -62,6 +63,34 @@
 
 static err_t netconn_close_shutdown(struct netconn *conn, u8_t how);
 
+
+/**
+ * Call the lower part of a netconn_* function
+ * This function is then running in the thread context
+ * of tcpip_thread and has exclusive access to lwIP core code.
+ *
+ * @param apimsg a struct containing the function to call and its parameters
+ * @return ERR_OK if the function was called, another err_t if not
+ */
+static err_t
+tcpip_apimsg(struct api_msg *apimsg)
+{
+#ifdef LWIP_DEBUG
+  /* catch functions that don't set err */
+  apimsg->msg.err = ERR_VAL;
+#endif
+#if LWIP_NETCONN_SEM_PER_THREAD
+  apimsg->msg.op_completed_sem = LWIP_NETCONN_THREAD_SEM_GET();
+  LWIP_ASSERT("netconn semaphore not initialized",
+    sys_sem_valid(apimsg->msg.op_completed_sem));
+#endif
+  
+  if (tcpip_send_api_msg(apimsg->function, &apimsg->msg, LWIP_API_MSG_SEM(&apimsg->msg)) == ERR_OK) {
+    return apimsg->msg.err;
+  }
+  return ERR_VAL;
+}
+
 /**
  * Create a new netconn (of a specific type) that has a callback function.
  * The corresponding pcb is also created.
diff --git a/src/api/tcpip.c b/src/api/tcpip.c
index 22f2cbd0..14f609c0 100644
--- a/src/api/tcpip.c
+++ b/src/api/tcpip.c
@@ -307,11 +307,10 @@ tcpip_untimeout(sys_timeout_handler h, void *arg)
  *
  * @param fn Function to be called from TCPIP thread
  * @param apimsg argument to API function
- * @param sem Semaphore to wait on
  * @return ERR_OK if the function was called, another err_t if not
  */
 err_t
-tcpip_send_api_msg(api_msg_fn fn, void *apimsg, sys_sem_t* sem)
+tcpip_send_api_msg(tcpip_callback_fn fn, void *apimsg, sys_sem_t* sem)
 {
   if (sys_mbox_valid_val(mbox)) {
     TCPIP_MSG_VAR_DECLARE(msg);
@@ -328,35 +327,6 @@ tcpip_send_api_msg(api_msg_fn fn, void *apimsg, sys_sem_t* sem)
   return ERR_VAL;
 }
 
-#if LWIP_NETCONN || LWIP_SOCKET
-/**
- * Call the lower part of a netconn_* function
- * This function is then running in the thread context
- * of tcpip_thread and has exclusive access to lwIP core code.
- *
- * @param apimsg a struct containing the function to call and its parameters
- * @return ERR_OK if the function was called, another err_t if not
- */
-err_t
-tcpip_apimsg(struct api_msg *apimsg)
-{
-#ifdef LWIP_DEBUG
-  /* catch functions that don't set err */
-  apimsg->msg.err = ERR_VAL;
-#endif
-#if LWIP_NETCONN_SEM_PER_THREAD
-  apimsg->msg.op_completed_sem = LWIP_NETCONN_THREAD_SEM_GET();
-  LWIP_ASSERT("netconn semaphore not initialized",
-    sys_sem_valid(apimsg->msg.op_completed_sem));
-#endif
-  
-  if (tcpip_send_api_msg(apimsg->function, &apimsg->msg, LWIP_API_MSG_SEM(&apimsg->msg)) == ERR_OK) {
-    return apimsg->msg.err;
-  }
-  return ERR_VAL;
-}
-#endif /* LWIP_NETCONN || LWIP_SOCKET */
-
 /**
  * Allocate a structure for a static callback message and initialize it.
  * This is intended to be used to send "static" messages from interrupt context.
diff --git a/src/include/lwip/priv/api_msg.h b/src/include/lwip/priv/api_msg.h
index df3deef5..0aaa4e68 100644
--- a/src/include/lwip/priv/api_msg.h
+++ b/src/include/lwip/priv/api_msg.h
@@ -186,6 +186,35 @@ struct dns_api_msg {
 };
 #endif /* LWIP_DNS */
 
+#if LWIP_TCPIP_CORE_LOCKING
+#ifdef LWIP_DEBUG
+#define TCIP_APIMSG_SET_ERR(m, e) (m)->msg.err = e  /* catch functions that don't set err */
+#else
+#define TCIP_APIMSG_SET_ERR(m, e)
+#endif
+#if LWIP_NETCONN_SEM_PER_THREAD
+#define TCPIP_APIMSG_SET_SEM(m) ((m)->msg.op_completed_sem = LWIP_NETCONN_THREAD_SEM_GET())
+#else
+#define TCPIP_APIMSG_SET_SEM(m)
+#endif
+#define TCPIP_APIMSG_NOERR(m,f) do { \
+  TCIP_APIMSG_SET_ERR(m, ERR_VAL); \
+  TCPIP_APIMSG_SET_SEM(m); \
+  LOCK_TCPIP_CORE(); \
+  f(&((m)->msg)); \
+  UNLOCK_TCPIP_CORE(); \
+} while(0)
+#define TCPIP_APIMSG(m,f,e)   do { \
+  TCPIP_APIMSG_NOERR(m,f); \
+  (e) = (m)->msg.err; \
+} while(0)
+#define TCPIP_APIMSG_ACK(m)   NETCONN_SET_SAFE_ERR((m)->conn, (m)->err)
+#else /* LWIP_TCPIP_CORE_LOCKING */
+#define TCPIP_APIMSG_NOERR(m,f) do { (m)->function = f; tcpip_apimsg(m); } while(0)
+#define TCPIP_APIMSG(m,f,e)   do { (m)->function = f; (e) = tcpip_apimsg(m); } while(0)
+#define TCPIP_APIMSG_ACK(m)   do { NETCONN_SET_SAFE_ERR((m)->conn, (m)->err); sys_sem_signal(LWIP_API_MSG_SEM(m)); } while(0)
+#endif /* LWIP_TCPIP_CORE_LOCKING */
+
 void lwip_netconn_do_newconn         (void *m);
 void lwip_netconn_do_delconn         (void *m);
 void lwip_netconn_do_bind            (void *m);
diff --git a/src/include/lwip/priv/tcpip_priv.h b/src/include/lwip/priv/tcpip_priv.h
index f38bdec2..375e403b 100644
--- a/src/include/lwip/priv/tcpip_priv.h
+++ b/src/include/lwip/priv/tcpip_priv.h
@@ -37,9 +37,7 @@
 #if !NO_SYS /* don't build if not configured for use in lwipopts.h */
 
 #include "lwip/tcpip.h"
-#include "lwip/priv/api_msg.h"
 #include "lwip/pbuf.h"
-#include "lwip/api.h"
 #include "lwip/sys.h"
 #include "lwip/timers.h"
 #include "lwip/netif.h"
@@ -59,37 +57,11 @@ extern "C" {
 extern sys_mutex_t lock_tcpip_core;
 #define LOCK_TCPIP_CORE()     sys_mutex_lock(&lock_tcpip_core)
 #define UNLOCK_TCPIP_CORE()   sys_mutex_unlock(&lock_tcpip_core)
-#ifdef LWIP_DEBUG
-#define TCIP_APIMSG_SET_ERR(m, e) (m)->msg.err = e  /* catch functions that don't set err */
-#else
-#define TCIP_APIMSG_SET_ERR(m, e)
-#endif
-#if LWIP_NETCONN_SEM_PER_THREAD
-#define TCPIP_APIMSG_SET_SEM(m) ((m)->msg.op_completed_sem = LWIP_NETCONN_THREAD_SEM_GET())
-#else
-#define TCPIP_APIMSG_SET_SEM(m)
-#endif
-#define TCPIP_APIMSG_NOERR(m,f) do { \
-  TCIP_APIMSG_SET_ERR(m, ERR_VAL); \
-  TCPIP_APIMSG_SET_SEM(m); \
-  LOCK_TCPIP_CORE(); \
-  f(&((m)->msg)); \
-  UNLOCK_TCPIP_CORE(); \
-} while(0)
-#define TCPIP_APIMSG(m,f,e)   do { \
-  TCPIP_APIMSG_NOERR(m,f); \
-  (e) = (m)->msg.err; \
-} while(0)
-#define TCPIP_APIMSG_ACK(m)   NETCONN_SET_SAFE_ERR((m)->conn, (m)->err)
 #else /* LWIP_TCPIP_CORE_LOCKING */
 #define LOCK_TCPIP_CORE()
 #define UNLOCK_TCPIP_CORE()
-#define TCPIP_APIMSG_NOERR(m,f) do { (m)->function = f; tcpip_apimsg(m); } while(0)
-#define TCPIP_APIMSG(m,f,e)   do { (m)->function = f; (e) = tcpip_apimsg(m); } while(0)
-#define TCPIP_APIMSG_ACK(m)   do { NETCONN_SET_SAFE_ERR((m)->conn, (m)->err); sys_sem_signal(LWIP_API_MSG_SEM(m)); } while(0)
 #endif /* LWIP_TCPIP_CORE_LOCKING */
 
-
 #if LWIP_MPU_COMPATIBLE
 #define API_VAR_REF(name)               (*(name))
 #define API_VAR_DECLARE(type, name)     type * name
@@ -122,12 +94,7 @@ extern sys_mutex_t lock_tcpip_core;
 #define API_EXPR_DEREF(expr)            *(expr)
 #endif /* LWIP_MPU_COMPATIBLE */
 
-#if LWIP_NETCONN || LWIP_SOCKET
-err_t tcpip_apimsg(struct api_msg *apimsg);
-#endif /* LWIP_NETCONN || LWIP_SOCKET */
-
-typedef void (*api_msg_fn)(void *msg);
-err_t tcpip_send_api_msg(api_msg_fn fn, void *apimsg, sys_sem_t* sem);
+err_t tcpip_send_api_msg(tcpip_callback_fn fn, void *apimsg, sys_sem_t* sem);
 
 enum tcpip_msg_type {
   TCPIP_MSG_API,
@@ -144,7 +111,7 @@ struct tcpip_msg {
   enum tcpip_msg_type type;
   union {
     struct {
-      api_msg_fn function;
+      tcpip_callback_fn function;
       void* msg;
     } api;
     struct {