diff --git a/mne/_fiff/meas_info.py b/mne/_fiff/meas_info.py
index 1714db42c47..587b1740034 100644
--- a/mne/_fiff/meas_info.py
+++ b/mne/_fiff/meas_info.py
@@ -2799,7 +2799,8 @@ def write_meas_info(fid, info, data_type=None, reset_range=True):
     if info.get("device_info") is not None:
         start_block(fid, FIFF.FIFFB_DEVICE)
         di = info["device_info"]
-        write_string(fid, FIFF.FIFF_DEVICE_TYPE, di["type"])
+        if di.get("type") is not None:
+            write_string(fid, FIFF.FIFF_DEVICE_TYPE, di["type"])
         for key in ("model", "serial", "site"):
             if di.get(key) is not None:
                 write_string(fid, getattr(FIFF, "FIFF_DEVICE_" + key.upper()), di[key])
diff --git a/mne/conftest.py b/mne/conftest.py
index 66197600270..2a54d1396c8 100644
--- a/mne/conftest.py
+++ b/mne/conftest.py
@@ -175,6 +175,8 @@ def pytest_configure(config):
     ignore:__array_wrap__ must accept context and return_scalar arguments.*:DeprecationWarning
     # nibabel <-> NumPy 2.0
     ignore:__array__ implementation doesn't accept a copy.*:DeprecationWarning
+    # quantities via neo
+    ignore:The 'copy' argument in Quantity is deprecated.*:
     """  # noqa: E501
     for warning_line in warning_lines.split("\n"):
         warning_line = warning_line.strip()