diff --git a/bids-validator/bids_validator/bids_validator.py b/bids-validator/bids_validator/bids_validator.py
index d8ec7a3bb..846de9d11 100644
--- a/bids-validator/bids_validator/bids_validator.py
+++ b/bids-validator/bids_validator/bids_validator.py
@@ -1,5 +1,6 @@
 """Validation class for BIDS projects."""
 import logging
+import os
 import re
 from functools import lru_cache
 from itertools import chain
@@ -134,6 +135,9 @@ def parse(cls, path):
         if cls.regexes is None:
             cls._init_regexes()
 
+        if path.startswith(os.sep):
+            path = path.replace(os.sep, '/')
+
         if not path.startswith('/'):
             raise ValueError("Path must be relative to root of a BIDS dataset,"
                              " and must include a leading forward slash `/`.")