diff -aur asterisk-13.4.0.orig/formats/format_wav.c asterisk-13.4.0.patched/formats/format_wav.c
--- asterisk-13.4.0.orig/formats/format_wav.c	2015-06-04 19:20:51.000000000 +0600
+++ asterisk-13.4.0.patched/formats/format_wav.c	2016-11-19 18:21:31.957821553 +0700
@@ -326,8 +326,10 @@
 	   if we did, it would go here.  We also might want to check
 	   and be sure it's a valid file.  */
 	struct wav_desc *tmp = (struct wav_desc *)s->_private;
-	if ((tmp->maxlen = check_header(s->f, ast_format_get_sample_rate(s->fmt->format))) < 0)
+	int hz = ast_format_get_sample_rate(s->fmt->format);
+	if ((tmp->maxlen = check_header(s->f, hz)) < 0)
 		return -1;
+	tmp->hz = hz;
 	return 0;
 }