diff --git a/nih2mne/make_meg_bids.py b/nih2mne/make_meg_bids.py
index c84d198..81bfb3a 100755
--- a/nih2mne/make_meg_bids.py
+++ b/nih2mne/make_meg_bids.py
@@ -578,6 +578,17 @@ def get_subj_logger(subjid, log_dir=None, loglevel=logging.INFO):
     temp_dir=Path(args.bids_dir).parent / 'bids_prep_temp'
     temp_dir.mkdir(parents=True, exist_ok=True)
     
+    #
+    #   Data Check
+    #
+    assert op.exists(args.meg_input_dir)
+    if 'mri_brik' in args:
+        assert op.exists(args.mri_brik)
+    if 'mri_bsight' in args:
+        assert op.exists(args.mri_bsight)
+    if 'mri_bsight_elec' in args:
+        assert op.exists(args.mri_bsight_elec)
+    
     #
     #   Process MEG
     #