diff --git a/src/api/api_lib.c b/src/api/api_lib.c
index eb3053b8..10df873b 100644
--- a/src/api/api_lib.c
+++ b/src/api/api_lib.c
@@ -548,7 +548,6 @@ netconn_recv(struct netconn *conn, struct netbuf **new_buf)
   LWIP_ERROR("netconn_recv: invalid pointer", (new_buf != NULL), return ERR_ARG;);
   *new_buf = NULL;
   LWIP_ERROR("netconn_recv: invalid conn",    (conn != NULL),    return ERR_ARG;);
-  LWIP_ERROR("netconn_recv: invalid recvmbox", sys_mbox_valid(&conn->recvmbox), return ERR_CONN;);
 
 #if LWIP_TCP
 #if (LWIP_UDP || LWIP_RAW)