* we know about.
  */
 static const struct iw_ioctl_description standard_event[] = {
-       [IWEVTXDROP     - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVTXDROP)] = {
                .header_type    = IW_HEADER_TYPE_ADDR,
        },
-       [IWEVQUAL       - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVQUAL)] = {
                .header_type    = IW_HEADER_TYPE_QUAL,
        },
-       [IWEVCUSTOM     - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVCUSTOM)] = {
                .header_type    = IW_HEADER_TYPE_POINT,
                .token_size     = 1,
                .max_tokens     = IW_CUSTOM_MAX,
        },
-       [IWEVREGISTERED - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVREGISTERED)] = {
                .header_type    = IW_HEADER_TYPE_ADDR,
        },
-       [IWEVEXPIRED    - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVEXPIRED)] = {
                .header_type    = IW_HEADER_TYPE_ADDR,
        },
-       [IWEVGENIE      - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVGENIE)] = {
                .header_type    = IW_HEADER_TYPE_POINT,
                .token_size     = 1,
                .max_tokens     = IW_GENERIC_IE_MAX,
        },
-       [IWEVMICHAELMICFAILURE  - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVMICHAELMICFAILURE)] = {
                .header_type    = IW_HEADER_TYPE_POINT,
                .token_size     = 1,
                .max_tokens     = sizeof(struct iw_michaelmicfailure),
        },
-       [IWEVASSOCREQIE - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVASSOCREQIE)] = {
                .header_type    = IW_HEADER_TYPE_POINT,
                .token_size     = 1,
                .max_tokens     = IW_GENERIC_IE_MAX,
        },
-       [IWEVASSOCRESPIE        - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVASSOCRESPIE)] = {
                .header_type    = IW_HEADER_TYPE_POINT,
                .token_size     = 1,
                .max_tokens     = IW_GENERIC_IE_MAX,
        },
-       [IWEVPMKIDCAND  - IWEVFIRST] = {
+       [IW_EVENT_IDX(IWEVPMKIDCAND)] = {
                .header_type    = IW_HEADER_TYPE_POINT,
                .token_size     = 1,
                .max_tokens     = sizeof(struct iw_pmkid_cand),
                if (cmd_index < standard_ioctl_num)
                        descr = &(standard_ioctl[cmd_index]);
        } else {
-               cmd_index = cmd - IWEVFIRST;
+               cmd_index = IW_EVENT_IDX(cmd);
                if (cmd_index < standard_event_num)
                        descr = &(standard_event[cmd_index]);
        }