diff --git a/src/ctapipe_io_zfits/dl0.py b/src/ctapipe_io_zfits/dl0.py
index 9cbab80..605dfb5 100644
--- a/src/ctapipe_io_zfits/dl0.py
+++ b/src/ctapipe_io_zfits/dl0.py
@@ -236,8 +236,11 @@ def scheduling_blocks(self) -> Dict[int, SchedulingBlockContainer]:
         return self._scheduling_blocks
 
     def _generator(self):
-        for subarray_trigger in self._subarray_trigger_file.SubarrayEvents:
+        for count, subarray_trigger in enumerate(
+            self._subarray_trigger_file.SubarrayEvents
+        ):
             array_event = ArrayEventContainer(
+                count=count,
                 index=EventIndexContainer(
                     obs_id=subarray_trigger.obs_id, event_id=subarray_trigger.event_id
                 ),
@@ -337,7 +340,7 @@ def observation_blocks(self) -> Dict[int, ObservationBlockContainer]:
     def scheduling_blocks(self) -> Dict[int, SchedulingBlockContainer]:
         return self._scheduling_blocks
 
-    def _fill_event(self, zfits_event) -> ArrayEventContainer:
+    def _fill_event(self, count, zfits_event) -> ArrayEventContainer:
         tel_id = self.tel_id
         # until ctapipe allows telescope event sources
         # we have to fill an arrayevent with just one telescope here
@@ -345,6 +348,7 @@ def _fill_event(self, zfits_event) -> ArrayEventContainer:
             zfits_event.event_time_s, zfits_event.event_time_qns
         )
         array_event = ArrayEventContainer(
+            count=count,
             index=EventIndexContainer(
                 obs_id=self.obs_id,
                 event_id=zfits_event.event_id,
@@ -364,5 +368,5 @@ def _fill_event(self, zfits_event) -> ArrayEventContainer:
         return array_event
 
     def _generator(self):
-        for event in self._multi_file:
-            yield self._fill_event(event)
+        for count, zfits_event in enumerate(self._multi_file):
+            yield self._fill_event(count, zfits_event)
diff --git a/src/ctapipe_io_zfits/tests/test_dl0.py b/src/ctapipe_io_zfits/tests/test_dl0.py
index c5f37e6..3f420c6 100644
--- a/src/ctapipe_io_zfits/tests/test_dl0.py
+++ b/src/ctapipe_io_zfits/tests/test_dl0.py
@@ -31,7 +31,8 @@ def test_subarray_events(dummy_dl0):
 
     with EventSource(dummy_dl0) as source:
         n_read = 0
-        for array_event in source:
+        for i, array_event in enumerate(source):
+            assert array_event.count == i
             assert array_event.index.obs_id == 456
             assert array_event.index.event_id == n_read + 1
             dt = np.abs(array_event.trigger.time - time).to(u.ns)
@@ -74,7 +75,8 @@ def test_telescope_event_source(dummy_tel_file):
     with EventSource(dummy_tel_file) as source:
         assert isinstance(source, ProtozfitsDL0TelescopeEventSource)
 
-        for event in source:
+        for i, event in enumerate(source):
+            assert event.count == i
             assert event.dl0.tel.keys() == {1}