diff --git a/selfdrive/selfdrived/alertmanager.py b/selfdrive/selfdrived/alertmanager.py
index 4a406d3962cbf4..ac1006ff258c01 100644
--- a/selfdrive/selfdrived/alertmanager.py
+++ b/selfdrive/selfdrived/alertmanager.py
@@ -27,10 +27,13 @@ class AlertEntry:
   alert: Alert | None = None
   start_frame: int = -1
   end_frame: int = -1
+  added_frame: int = -1
 
   def active(self, frame: int) -> bool:
     return frame <= self.end_frame
 
+  def just_added(self, frame: int) -> bool:
+    return self.active(frame) and frame == (self.added_frame + 1)
 
 class AlertManager:
   def __init__(self):
@@ -41,10 +44,11 @@ def add_many(self, frame: int, alerts: list[Alert]) -> None:
     for alert in alerts:
       entry = self.alerts[alert.alert_type]
       entry.alert = alert
-      if not entry.active(frame):
+      if not entry.just_added(frame):
         entry.start_frame = frame
       min_end_frame = entry.start_frame + alert.duration
       entry.end_frame = max(frame + 1, min_end_frame)
+      entry.added_frame = frame
 
   def process_alerts(self, frame: int, clear_event_types: set):
     ae = AlertEntry()
diff --git a/selfdrive/selfdrived/tests/test_alertmanager.py b/selfdrive/selfdrived/tests/test_alertmanager.py
index b75a4d1cbe3b3b..030b7d4515c2f2 100644
--- a/selfdrive/selfdrived/tests/test_alertmanager.py
+++ b/selfdrive/selfdrived/tests/test_alertmanager.py
@@ -32,8 +32,27 @@ def test_duration(self):
         for frame in range(duration+10):
           if frame < add_duration:
             AM.add_many(frame, [alert, ])
-          AM.process_alerts(frame, {})
+          AM.process_alerts(frame, set())
 
           shown = AM.current_alert != EmptyAlert
           should_show = frame <= show_duration
           assert shown == should_show, f"{frame=} {add_duration=} {duration=}"
+
+      # check one case:
+      # - if alert is re-added to AM before it ends the duration is extended
+      if duration > 1:
+        AM = AlertManager()
+        show_duration = duration * 2
+        for frame in range(duration * 2 + 10):
+          if frame == 0:
+            AM.add_many(frame, [alert, ])
+
+          if frame == duration:
+            # add alert one frame before it ends
+            assert AM.current_alert == alert
+            AM.add_many(frame, [alert, ])
+          AM.process_alerts(frame, set())
+
+          shown = AM.current_alert != EmptyAlert
+          should_show = frame <= show_duration
+          assert shown == should_show, f"{frame=} {duration=}"
diff --git a/selfdrive/test/process_replay/ref_commit b/selfdrive/test/process_replay/ref_commit
index 0ec17758ac914d..22cae4b8ccfd33 100644
--- a/selfdrive/test/process_replay/ref_commit
+++ b/selfdrive/test/process_replay/ref_commit
@@ -1 +1 @@
-bfbdd4706abcf5757790526d99d0000644017b1e
\ No newline at end of file
+36bb37715542677db4a42464128ca10968f2c589
\ No newline at end of file