-static rrd_queue_t *queue_head = NULL;
-static rrd_queue_t *queue_tail = NULL;
-static rrd_queue_t *flushq_head = NULL;
-static rrd_queue_t *flushq_tail = NULL;
+static rrd_queue_t *queue_head;
+static rrd_queue_t *queue_tail;
+static rrd_queue_t *flushq_head;
+static rrd_queue_t *flushq_tail;