diff --git a/dandi/bids_validator_xs.py b/dandi/bids_validator_xs.py
index ea0d82355..9ccee19cf 100644
--- a/dandi/bids_validator_xs.py
+++ b/dandi/bids_validator_xs.py
@@ -130,7 +130,7 @@ def _extension_safety(extension):
     """
     if extension == "None":
         return ""
-    if "*" in extension:
+    if "." in extension:
         extension = extension.replace(".", "\\.")
     if "*" in extension:
         extension = extension.replace("*", ".*?")
diff --git a/dandi/tests/test_bids_validator_xs.py b/dandi/tests/test_bids_validator_xs.py
index 43d106901..4d532431a 100644
--- a/dandi/tests/test_bids_validator_xs.py
+++ b/dandi/tests/test_bids_validator_xs.py
@@ -98,7 +98,8 @@ def test__add_extensions():
     assert (
         _regex_string == "sub-(?P=subject)(|_ses-(?P=session))"
         "_sample-(?P<sample>([a-z,A-Z,0-9]*?))"
-        "(|_acq-(?P<acquisition>([a-z,A-Z,0-9]*?)))_photo\\.(jpg|png|tif)"
+        "(|_acq-(?P<acquisition>([a-z,A-Z,0-9]*?)))"
+        "_photo(\\.jpg|\\.png|\\.tif)"
     )