Index: res_monitor.c
===================================================================
--- res_monitor.c       (revision 44152)
+++ res_monitor.c       (working copy)
@@ -575,8 +575,6 @@
                chan->monitor->joinfiles = turnon;
 }

-#define IS_NULL_STRING(string) ((!(string)) || (ast_strlen_zero((string))))
-
 enum MONITOR_PAUSING_ACTION
 {
        MONITOR_ACTION_PAUSE,
@@ -588,7 +586,7 @@
        struct ast_channel *c = NULL;
        char *name = astman_get_header(m, "Channel");

-       if (IS_NULL_STRING(name)) {
+       if (ast_strlen_zero(name)) {
                astman_send_error(s, m, "No channel specified");
                return -1;