diff --git a/mne_bids/write.py b/mne_bids/write.py
index a736417b05..799748d680 100644
--- a/mne_bids/write.py
+++ b/mne_bids/write.py
@@ -1351,7 +1351,10 @@ def write_raw_bids(raw, bids_basename, bids_root, events_data=None,
         copyfile_kit(raw_fname, bids_fname, subject_id, session_id,
                      task, run, raw._init_kwargs)
     elif ext == '.nirx':
-        _write_raw_fif(raw, bids_fname.replace(ext, '.fif'))
+        _write_raw_fif(raw, bids_fname.replace(ext, '_raw.fif'))
+        # This is a temporary hack until snirf io is implemented
+        os.rename(bids_fname.replace(ext, '_raw.fif'),
+                  bids_fname.replace(ext, '.snirf'))
     else:
         sh.copyfile(raw_fname, bids_fname)