diff --git a/src/gps/RTC.cpp b/src/gps/RTC.cpp
index ceb79eebf..e208e2df9 100644
--- a/src/gps/RTC.cpp
+++ b/src/gps/RTC.cpp
@@ -132,6 +132,10 @@ RTCSetResult perhapsSetRTC(RTCQuality q, const struct timeval *tv, bool forceUpd
     if (tv->tv_sec < BUILD_EPOCH) {
         LOG_WARN("Ignore time (%ld) before build epoch (%ld)!", printableEpoch, BUILD_EPOCH);
         return RTCSetResultInvalidTime;
+    } else if (tv->tv_sec > (BUILD_EPOCH + FORTY_YEARS)) {
+        LOG_WARN("Ignore time (%ld) too far in the future (build epoch: %ld, max allowed: %ld)!", printableEpoch, BUILD_EPOCH,
+                 BUILD_EPOCH + FORTY_YEARS);
+        return RTCSetResultInvalidTime;
     }
 #endif
 
@@ -250,6 +254,10 @@ RTCSetResult perhapsSetRTC(RTCQuality q, struct tm &t)
     if (tv.tv_sec < BUILD_EPOCH) {
         LOG_WARN("Ignore time (%ld) before build epoch (%ld)!", printableEpoch, BUILD_EPOCH);
         return RTCSetResultInvalidTime;
+    } else if (tv.tv_sec > (BUILD_EPOCH + FORTY_YEARS)) {
+        LOG_WARN("Ignore time (%ld) too far in the future (build epoch: %ld, max allowed: %ld)!", printableEpoch, BUILD_EPOCH,
+                 BUILD_EPOCH + FORTY_YEARS);
+        return RTCSetResultInvalidTime;
     }
 #endif
 
diff --git a/src/gps/RTC.h b/src/gps/RTC.h
index 010be6886..03350823c 100644
--- a/src/gps/RTC.h
+++ b/src/gps/RTC.h
@@ -55,3 +55,6 @@ time_t gm_mktime(struct tm *tm);
 #define SEC_PER_DAY 86400
 #define SEC_PER_HOUR 3600
 #define SEC_PER_MIN 60
+#ifdef BUILD_EPOCH
+#define FORTY_YEARS (40UL * 365 * SEC_PER_DAY) // probably time to update your firmware
+#endif