diff --git a/mne_bids/read.py b/mne_bids/read.py
index 365cdd220..0836989e5 100644
--- a/mne_bids/read.py
+++ b/mne_bids/read.py
@@ -331,6 +331,8 @@ def _handle_scans_reading(scans_fname, raw, bids_path):
         if "." not in acq_time:
             # acquisition time ends with '.%fZ' microseconds string
             acq_time += ".0Z"
+        if "Z" not in acq_time:
+            acq_time += "Z"
         acq_time = datetime.strptime(acq_time, "%Y-%m-%dT%H:%M:%S.%fZ")
         acq_time = acq_time.replace(tzinfo=timezone.utc)