diff --git a/libraries/AP_InertialSensor/AP_InertialSensor_Invensensev3.cpp b/libraries/AP_InertialSensor/AP_InertialSensor_Invensensev3.cpp
index 5f1e8eeec14..b5e3757890e 100644
--- a/libraries/AP_InertialSensor/AP_InertialSensor_Invensensev3.cpp
+++ b/libraries/AP_InertialSensor/AP_InertialSensor_Invensensev3.cpp
@@ -1343,8 +1343,8 @@ bool AP_InertialSensor_Invensensev3::hardware_init(void)
         }
 
         // enable RTC MODE (bit5). On 56686 this register is OTP_HEATER_RTC_CONFIG
-        // with live bits in [4:0] — RMW so those are preserved. Keep the
-        // historical blind 0x20 write on 45686 CLKIN boards in this PR.
+        // with live bits in [4:0] -- RMW so those are preserved. 45686: keep the
+        // blind 0x20 write (unchanged behaviour).
         if (inv3_type == Invensensev3_Type::ICM56686) {
             const uint8_t rtc = register_read(reg456(INV3REG_456_RTC_CONFIG));
             register_write(reg456(INV3REG_456_RTC_CONFIG), rtc | (0x1<<5U));