Index: main/format.c
===================================================================
--- main/format.c	(revision 407675)
+++ main/format.c	(working copy)
@@ -42,6 +42,7 @@
 #include "asterisk/cli.h"
 #include "asterisk/rtp_engine.h"
 #include "asterisk/config.h"
+#include "asterisk/channel.h"
 
 #define FORMAT_CONFIG "codecs.conf"
 
@@ -1113,7 +1114,7 @@
 static void format_attr_shutdown(void)
 {
 	ast_cli_unregister_multiple(my_clis, ARRAY_LEN(my_clis));
-	if (interfaces) {
+	if (interfaces && !ast_undestroyed_channels()) {
 		ao2_ref(interfaces, -1);
 		interfaces = NULL;
 	}