diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -1301,7 +1301,7 @@
 		pglen = m_epg_pagelen(m, i, pgoff);
 		if (off < pglen) {
 			count = min(pglen - off, len);
-			p = (void *)PHYS_TO_DMAP(m->m_epg_pa[i] + pgoff);
+			p = (void *)PHYS_TO_DMAP(m->m_epg_pa[i] + pgoff + off);
 			rval = f(arg, p, count);
 			if (rval)
 				return (rval);