diff --git a/src/main/blackbox/blackbox.c b/src/main/blackbox/blackbox.c
index ad787be2e4..a5a722726b 100644
--- a/src/main/blackbox/blackbox.c
+++ b/src/main/blackbox/blackbox.c
@@ -1187,15 +1187,15 @@ static bool sendFieldDefinition(char mainFrameChar, char deltaFrameChar, const v
 // Buf must be at least FORMATTED_DATE_TIME_BUFSIZE
 STATIC_UNIT_TESTED char *blackboxGetStartDateTime(char *buf)
 {
-    #ifdef USE_RTC_TIME
+#ifdef USE_RTC_TIME
     dateTime_t dt;
     // rtcGetDateTime will fill dt with 0000-01-01T00:00:00
     // when time is not known.
     rtcGetDateTime(&dt);
     dateTimeFormatLocal(buf, &dt);
-    #else
+#else
     buf = "0000-01-01T00:00:00.000";
-    #endif
+#endif
 
     return buf;
 }
diff --git a/src/main/common/time.c b/src/main/common/time.c
index c15f104626..707cad7c38 100644
--- a/src/main/common/time.c
+++ b/src/main/common/time.c
@@ -200,7 +200,8 @@ bool dateTimeFormatUTC(char *buf, dateTime_t *dt)
 
 bool dateTimeFormatLocal(char *buf, dateTime_t *dt)
 {
-    return dateTimeFormat(buf, dt, timeConfig()->tz_offsetMinutes, false);
+    const int16_t timezoneOffset = rtcIsDateTimeValid(dt) ? timeConfig()->tz_offsetMinutes : 0;
+    return dateTimeFormat(buf, dt, timezoneOffset, false);
 }
 
 bool dateTimeFormatLocalShort(char *buf, dateTime_t *dt)