--- a/sys/dev/netif/ath/ath/if_ath_spectral.c
+++ b/sys/dev/netif/ath/ath/if_ath_spectral.c
@@ -234,6 +234,14 @@
 				error = EINVAL;
 				break;
 			}
+			/* ATH_DIAG_IN not set: no parameters were copied in
+			 * (ad_in_size alone does not make indata valid;
+			 * mirrors the indata == NULL check that
+			 * ENABLE_AT_RESET already has below). */
+			if (indata == NULL) {
+				error = EINVAL;
+				break;
+			}
 			pe = (HAL_SPECTRAL_PARAM *) indata;
 			ath_hal_spectral_configure(sc->sc_ah, pe);
 			/* Save a local copy of the updated parameters */