diff --git a/src/ctapipe_io_lst/multifiles.py b/src/ctapipe_io_lst/multifiles.py
index b8165f01..c92a7134 100644
--- a/src/ctapipe_io_lst/multifiles.py
+++ b/src/ctapipe_io_lst/multifiles.py
@@ -146,7 +146,7 @@ def _load_next_subrun(self, stream):
 
         if stream is None:
             path = self.path
-            stream = self.file_info.stream
+            stream = self.file_info.stream if self.file_info is not None else None
         else:
             self.current_subrun[stream] += 1
 
diff --git a/src/ctapipe_io_lst/tests/test_lsteventsource.py b/src/ctapipe_io_lst/tests/test_lsteventsource.py
index 90bea5f1..7112ce99 100644
--- a/src/ctapipe_io_lst/tests/test_lsteventsource.py
+++ b/src/ctapipe_io_lst/tests/test_lsteventsource.py
@@ -437,3 +437,17 @@ def test_evb_calibrated_data():
             assert np.all(e.calibration.tel[1].dl1.time_shift != 0)
 
         assert read_events == 200
+
+
+def test_arbitrary_filename(tmp_path):
+    from ctapipe_io_lst import LSTEventSource
+    path = tmp_path / "some_name_not_matching_the_lst_pattern.fits.fz"
+    path.write_bytes(test_r0_path_all_streams.read_bytes())
+
+    assert LSTEventSource.is_compatible(path)
+
+    with LSTEventSource(path, pointing_information=False, apply_drs4_corrections=False) as source:
+        n_read = 0
+        for _ in source:
+            n_read += 1
+        assert n_read == n_read