--- a/ath/if_ath.c
+++ b/ath/if_ath.c
@@ -4915,7 +4915,7 @@
* capability info and arrange for a mode change
* if needed.
*/
- if (sc->sc_dturbo) {
+ if (sc->sc_dturbo && NULL != avp->av_boff.bo_tim) {
u_int8_t dtim;
dtim = ((avp->av_boff.bo_tim[2] == 1) ||
(avp->av_boff.bo_tim[3] == 1));