diff --git a/common/time_helpers.py b/common/time_helpers.py
index 8564e270c..c709182d4 100644
--- a/common/time_helpers.py
+++ b/common/time_helpers.py
@@ -2,6 +2,7 @@ import datetime
 from pathlib import Path
 
 MIN_DATE = datetime.datetime(year=2025, month=2, day=21)
+MAX_DATE = datetime.datetime(year=2035, month=1, day=1)
 
 def min_date():
   # on systemd systems, the default time is the systemd build time
@@ -12,4 +13,4 @@ def min_date():
   return MIN_DATE
 
 def system_time_valid():
-  return datetime.datetime.now() > min_date()
+  return min_date() < datetime.datetime.now() < MAX_DATE
diff --git a/system/qcomgpsd/qcomgpsd.py b/system/qcomgpsd/qcomgpsd.py
index 82b9ea927..47d64ff4e 100755
--- a/system/qcomgpsd/qcomgpsd.py
+++ b/system/qcomgpsd/qcomgpsd.py
@@ -357,6 +357,9 @@ def main() -> NoReturn:
       report = unpack_position(log_payload)
       if report["u_PosSource"] != 2:
         continue
+      # uint16_t max is an invalid sentinel value from the modem
+      if report['w_GpsWeekNumber'] >= 0xFFFF:
+        continue
       vNED = [report["q_FltVelEnuMps[1]"], report["q_FltVelEnuMps[0]"], -report["q_FltVelEnuMps[2]"]]
       vNEDsigma = [report["q_FltVelSigmaMps[1]"], report["q_FltVelSigmaMps[0]"], -report["q_FltVelSigmaMps[2]"]]
 
diff --git a/system/timed.py b/system/timed.py
index b7131b04c..c74ba51da 100755
--- a/system/timed.py
+++ b/system/timed.py
@@ -5,7 +5,7 @@ import time
 from typing import NoReturn
 
 import cereal.messaging as messaging
-from openpilot.common.time_helpers import min_date, system_time_valid
+from openpilot.common.time_helpers import min_date, MAX_DATE, system_time_valid
 from openpilot.common.swaglog import cloudlog
 from openpilot.common.params import Params
 from openpilot.common.gps import get_gps_location_service
@@ -52,7 +52,7 @@ def main() -> NoReturn:
       continue
     if not gps.hasFix:
       continue
-    if gps_time < min_date():
+    if gps_time < min_date() or gps_time > MAX_DATE:
       continue
 
     set_time(gps_time)