diff --git a/doc/whats_new.rst b/doc/whats_new.rst
index 1824c82b8..9fa966250 100644
--- a/doc/whats_new.rst
+++ b/doc/whats_new.rst
@@ -21,6 +21,7 @@ The following authors contributed for the first time. Thank you so much! 🤩
 
 The following authors had contributed before. Thank you for sticking around! 🤘
 
+* `Daniel McCloy`_
 * `Stefan Appelhoff`_
 
 Detailed list of changes
@@ -44,7 +45,7 @@ Detailed list of changes
 🪲 Bug fixes
 ^^^^^^^^^^^^
 
-- nothing yet
+- When anonymizing the date of a recording, MNE-BIDS will no longer error during `~mne_bids.write_raw_bids` if passing a `~mne.io.Raw` instance to ``empty_room``. By `Daniel McCloy`_ (:gh:`1270`)
 
 ⚕️ Code health
 ^^^^^^^^^^^^^^
diff --git a/mne_bids/tests/test_write.py b/mne_bids/tests/test_write.py
index 680fd2fe3..a586a1d69 100644
--- a/mne_bids/tests/test_write.py
+++ b/mne_bids/tests/test_write.py
@@ -3151,13 +3151,16 @@ def test_anonymize(subject, dir_name, fname, reader, tmp_path, _bids_validate):
     # handle different edge cases
     if subject == "emptyroom":
         bids_path.update(task="noise", session=raw_date, suffix="meg", datatype="meg")
+        erm = dict()
     else:
         bids_path.update(task="task", suffix="eeg", datatype="eeg")
+        # make sure anonymization works when also writing empty room file
+        erm = dict(empty_room=raw.copy())
     daysback_min, daysback_max = get_anonymization_daysback(raw)
     anonymize = dict(daysback=daysback_min + 1)
     orig_bids_path = bids_path.copy()
     bids_path = write_raw_bids(
-        raw, bids_path, overwrite=True, anonymize=anonymize, verbose=False
+        raw, bids_path, overwrite=True, anonymize=anonymize, verbose=False, **erm
     )
     # emptyroom recordings' session should match the recording date
     if subject == "emptyroom":
diff --git a/mne_bids/write.py b/mne_bids/write.py
index c5d95b7dd..eeaf49257 100644
--- a/mne_bids/write.py
+++ b/mne_bids/write.py
@@ -1814,7 +1814,7 @@ def write_raw_bids(
         er_bids_path = bids_path.copy().update(
             subject="emptyroom", session=er_session, task="noise", run=None
         )
-        write_raw_bids(
+        er_bids_path = write_raw_bids(
             raw=empty_room,
             bids_path=er_bids_path,
             events=None,