diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 28e1cc5db6f0..b74e957f28ce 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -933,7 +933,6 @@ extern int		nmbclusters;	/* Maximum number of clusters */
 struct uio;
 
 void		 m_adj(struct mbuf *, int);
-void		 m_align(struct mbuf *, int);
 int		 m_apply(struct mbuf *, int, int,
 		    int (*)(void *, void *, u_int), void *);
 int		 m_append(struct mbuf *, int, c_caddr_t);