diff --git a/vfprintf.c b/vfprintf.c
new file mode 100644
index 0000000..354406c
--- /dev/null
+++ b/vfprintf.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 1995
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that: (1) source code distributions
+ * retain the above copyright notice and this paragraph in its entirety, (2)
+ * distributions including binary code include the above copyright notice and
+ * this paragraph in its entirety in the documentation or other materials
+ * provided with the distribution, and (3) all advertising materials mentioning
+ * features or use of this software display the following acknowledgement:
+ * ``This product includes software developed by the University of California,
+ * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
+ * the University nor the names of its contributors may be used to endorse
+ * or promote products derived from this software without specific prior
+ * written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#ifndef lint
+static const char rcsid[] _U_ =
+    "@(#) $Header: /tcpdump/master/tcpdump/vfprintf.c,v 1.6 2003/11/16 09:36:45 guy Exp $ (LBL)";
+#endif
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <sys/types.h>
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "interface.h"
+
+/*
+ * Stock 4.3 doesn't have vfprintf.
+ * This routine is due to Chris Torek.
+ */
+vfprintf(f, fmt, args)
+	FILE *f;
+	char *fmt;
+	va_list args;
+{
+	int ret;
+
+	if ((f->_flag & _IOWRT) == 0) {
+		if (f->_flag & _IORW)
+			f->_flag |= _IOWRT;
+		else
+			return EOF;
+	}
+	ret = _doprnt(fmt, args, f);
+	return ferror(f) ? EOF : ret;
+}