diff --git a/src/gps/RTC.cpp b/src/gps/RTC.cpp
index 4a629d755..da20e28eb 100644
--- a/src/gps/RTC.cpp
+++ b/src/gps/RTC.cpp
@@ -143,7 +143,7 @@ RTCSetResult perhapsSetRTC(RTCQuality q, const struct timeval *tv, bool forceUpd
             lastTimeValidationWarning = millis();
         }
         return RTCSetResultInvalidTime;
-    } else if (tv->tv_sec > (time_t)(BUILD_EPOCH + FORTY_YEARS)) {
+    } else if ((uint64_t)tv->tv_sec > ((uint64_t)BUILD_EPOCH + FORTY_YEARS)) {
         if (Throttle::isWithinTimespanMs(lastTimeValidationWarning, TIME_VALIDATION_WARNING_INTERVAL_MS) == false) {
             // Calculate max allowed time safely to avoid overflow in logging
             uint64_t maxAllowedTime = (uint64_t)BUILD_EPOCH + FORTY_YEARS;
@@ -274,7 +274,7 @@ RTCSetResult perhapsSetRTC(RTCQuality q, struct tm &t)
             lastTimeValidationWarning = millis();
         }
         return RTCSetResultInvalidTime;
-    } else if (tv.tv_sec > (time_t)(BUILD_EPOCH + FORTY_YEARS)) {
+    } else if ((uint64_t)tv.tv_sec > ((uint64_t)BUILD_EPOCH + FORTY_YEARS)) {
         if (Throttle::isWithinTimespanMs(lastTimeValidationWarning, TIME_VALIDATION_WARNING_INTERVAL_MS) == false) {
             // Calculate max allowed time safely to avoid overflow in logging
             uint64_t maxAllowedTime = (uint64_t)BUILD_EPOCH + FORTY_YEARS;
diff --git a/src/gps/RTC.h b/src/gps/RTC.h
index 1ecde79ae..eca17bf35 100644
--- a/src/gps/RTC.h
+++ b/src/gps/RTC.h
@@ -56,5 +56,5 @@ time_t gm_mktime(struct tm *tm);
 #define SEC_PER_HOUR 3600
 #define SEC_PER_MIN 60
 #ifdef BUILD_EPOCH
-#define FORTY_YEARS (40ULL * 365 * SEC_PER_DAY) // Use 64-bit arithmetic to prevent overflow
+static constexpr uint64_t FORTY_YEARS = (40ULL * 365 * SEC_PER_DAY); // Use 64-bit arithmetic to prevent overflow
 #endif