diff --git a/src/algorithms/PVT/libs/rtcm.cc b/src/algorithms/PVT/libs/rtcm.cc
index e0a0c10a5..2d9e943d4 100644
--- a/src/algorithms/PVT/libs/rtcm.cc
+++ b/src/algorithms/PVT/libs/rtcm.cc
@@ -3402,6 +3402,13 @@ boost::posix_time::ptime Rtcm::compute_GPS_time(const Gps_Ephemeris& eph, double
 {
     const double gps_t = obs_time;
     boost::posix_time::time_duration t = boost::posix_time::milliseconds(static_cast<long>((gps_t + 604800 * static_cast<double>(eph.i_GPS_week % 1024)) * 1000));  // NOLINT(google-runtime-int)
+
+    if (eph.i_GPS_week < 512)
+        {
+            boost::posix_time::ptime p_time(boost::gregorian::date(2019, 4, 7), t);
+            return p_time;
+        }
+
     boost::posix_time::ptime p_time(boost::gregorian::date(1999, 8, 22), t);
     return p_time;
 }
@@ -3411,6 +3418,13 @@ boost::posix_time::ptime Rtcm::compute_GPS_time(const Gps_CNAV_Ephemeris& eph, d
 {
     const double gps_t = obs_time;
     boost::posix_time::time_duration t = boost::posix_time::milliseconds(static_cast<long>((gps_t + 604800 * static_cast<double>(eph.i_GPS_week % 1024)) * 1000));  // NOLINT(google-runtime-int)
+
+    if (eph.i_GPS_week < 512)
+        {
+            boost::posix_time::ptime p_time(boost::gregorian::date(2019, 4, 7), t);
+            return p_time;
+        }
+
     boost::posix_time::ptime p_time(boost::gregorian::date(1999, 8, 22), t);
     return p_time;
 }