Index: configure.ac
===================================================================
RCS file: /sources/global/global/configure.ac,v
retrieving revision 1.195
diff -u -p -r1.195 configure.ac
--- configure.ac	15 May 2017 06:15:00 -0000	1.195
+++ configure.ac	27 Sep 2017 13:34:53 -0000
@@ -115,6 +115,8 @@ AC_CHECK_SIZEOF(char)
 if test ${ac_cv_sizeof_char} != 1; then
 	AC_MSG_ERROR([Char size isn't 8 bit.])
 fi
+AC_CHECK_SIZEOF(long)
+AC_CHECK_SIZEOF(off_t)
 
 dnl Checks for library functions.
 AC_FUNC_ALLOCA
Index: libdb/mpool.c
===================================================================
RCS file: /sources/global/global/libdb/mpool.c,v
retrieving revision 1.8
diff -u -p -r1.8 mpool.c
--- libdb/mpool.c	13 Oct 2012 07:01:21 -0000	1.8
+++ libdb/mpool.c	27 Sep 2017 13:34:53 -0000
@@ -229,7 +229,11 @@ mpool_get(mp, pgno, flags)
 #ifdef STATISTICS
 	++mp->pageread;
 #endif
+#if SIZEOF_OFF_T > SIZEOF_LONG
+	off = (off_t)mp->pagesize * (off_t)pgno;
+#else
 	off = mp->pagesize * pgno;
+#endif
 #ifdef HAVE_PREAD
 	if ((nr = pread(mp->fd, bp->page, mp->pagesize, off)) != mp->pagesize) {
 		if (nr >= 0)
@@ -425,7 +429,11 @@ mpool_write(mp, bp)
 	if (mp->pgout)
 		(mp->pgout)(mp->pgcookie, bp->pgno, bp->page);
 
+#if SIZEOF_OFF_T > SIZEOF_LONG
+	off = (off_t)mp->pagesize * (off_t)bp->pgno;
+#else
 	off = mp->pagesize * bp->pgno;
+#endif
 #ifdef HAVE_PWRITE
 	if (pwrite(mp->fd, bp->page, mp->pagesize, off) != mp->pagesize)
 		return (RET_ERROR);