Index: pbx.c
===================================================================
--- pbx.c       (revision 32817)
+++ pbx.c       (working copy)
@@ -1891,11 +1891,15 @@
        char *parse;
        char *cur;
        int state;
+       const char *devicelist;

        ast_mutex_lock(&hintlock);

        for (hint = hints; hint; hint = hint->next) {
-               ast_copy_string(buf, ast_get_extension_app(hint->exten), sizeof(buf));
+               if (!(devicelist = ast_get_extension_app(hint->exten)))
+                       continue;
+
+               ast_copy_string(buf, devicelist, sizeof(buf));
                parse = buf;
                for (cur = strsep(&parse, "&"); cur; cur = strsep(&parse, "&")) {
                        if (strcasecmp(cur, device))