diff --git a/tasmota/settings.h b/tasmota/settings.h
index d5baaed93..cc0fd9bf3 100644
--- a/tasmota/settings.h
+++ b/tasmota/settings.h
@@ -118,7 +118,7 @@ typedef union {                            // Restricted by MISRA-C Rule 18.4 bu
     uint32_t network_ethernet : 1;         // bit 14 (v8.3.1.3)  - CMND_ETHERNET
     uint32_t tuyamcu_baudrate : 1;         // bit 15 (v8.3.1.6)  - SetOption97 - Set Baud rate for TuyaMCU serial communication (0 = 9600 or 1 = 115200)
     uint32_t rotary_uses_rules : 1;        // bit 16 (v8.3.1.6)  - SetOption98 - Use rules instead of light control
-    uint32_t spare17 : 1;
+    uint32_t zerocross_dimmer : 1;         // bit 17 (v8.3.1.4)  = SetOption99 - Enable zerocross dimmer on PWM DIMMER
     uint32_t spare18 : 1;
     uint32_t spare19 : 1;
     uint32_t spare20 : 1;