diff --git a/platform/cc2538dk/contiki-conf.h b/platform/cc2538dk/contiki-conf.h
index c91338849..ae7c3275d 100644
--- a/platform/cc2538dk/contiki-conf.h
+++ b/platform/cc2538dk/contiki-conf.h
@@ -42,6 +42,7 @@ typedef uint32_t rtimer_clock_t;
 /*---------------------------------------------------------------------------*/
 #define TSCH_CONF_HW_FRAME_FILTERING	0
 
+/* TODO: measure the delays, this are only estimations */
 #define RADIO_DELAY_BEFORE_TX     ((unsigned)US_TO_RTIMERTICKS(300))
 #define RADIO_DELAY_BEFORE_RX     ((unsigned)US_TO_RTIMERTICKS(100))
 #define RADIO_DELAY_BEFORE_DETECT 0