diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 2f19a61c774..b9f1c185f4a 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -345,6 +345,7 @@ static __inline void		 m_clget(struct mbuf *m, int how);
 static __inline void		*m_cljget(struct mbuf *m, int how, int size);
 static __inline void		 m_chtype(struct mbuf *m, short new_type);
 void				 mb_free_ext(struct mbuf *);
+static __inline struct mbuf	*m_last(struct mbuf *m);
 
 static __inline int
 m_gettype(int size)
@@ -579,6 +580,15 @@ m_chtype(struct mbuf *m, short new_type)
 	m->m_type = new_type;
 }
 
+static __inline struct mbuf *
+m_last(struct mbuf *m)
+{
+
+	while (m->m_next)
+		m = m->m_next;
+	return (m);
+}
+
 /*
  * mbuf, cluster, and external object allocation macros (for compatibility
  * purposes).