diff --git a/src/api/tcpip.c b/src/api/tcpip.c
index 37b2e652..29384b69 100644
--- a/src/api/tcpip.c
+++ b/src/api/tcpip.c
@@ -525,7 +525,7 @@ tcpip_init(void (* initfunc)(void *), void *arg)
  * @param p The pbuf (chain) to be dereferenced.
  */
 static void
-pub_free_int(void *p)
+pbuf_free_int(void *p)
 {
   struct pbuf *q = p;
   pbuf_free(q);
@@ -540,7 +540,7 @@ pub_free_int(void *p)
 err_t
 pbuf_free_callback(struct pbuf *p)
 {
-  return tcpip_callback_with_block(pub_free_int, p, 0);
+  return tcpip_callback_with_block(pbuf_free_int, p, 0);
 }
 
 /**
diff --git a/src/include/lwip/tcpip.h b/src/include/lwip/tcpip.h
index cb0fe0eb..0d295641 100644
--- a/src/include/lwip/tcpip.h
+++ b/src/include/lwip/tcpip.h
@@ -85,6 +85,7 @@ err_t tcpip_netifapi_lock(struct netifapi_msg *netifapimsg);
 err_t tcpip_callback_with_block(void (*f)(void *ctx), void *ctx, u8_t block);
 #define tcpip_callback(f, ctx)              tcpip_callback_with_block(f, ctx, 1)
 
+/* free pbufs or heap memory from another context without blocking */
 err_t pbuf_free_callback(struct pbuf *p);
 err_t mem_free_callback(void *m);