diff --git a/pytorch_pretrained_bert/file_utils.py b/pytorch_pretrained_bert/file_utils.py
index 0b5fc2c217..6954bec0e1 100644
--- a/pytorch_pretrained_bert/file_utils.py
+++ b/pytorch_pretrained_bert/file_utils.py
@@ -12,6 +12,7 @@ import shutil
 import tempfile
 from functools import wraps
 from hashlib import sha256
+import sys
 from io import open
 
 import boto3
@@ -60,6 +61,8 @@ def filename_to_url(filename, cache_dir=None):
     """
     if cache_dir is None:
         cache_dir = PYTORCH_PRETRAINED_BERT_CACHE
+    if sys.version_info[0] == 3 and isinstance(cache_dir, Path):
+        cache_dir = str(cache_dir)
 
     cache_path = os.path.join(cache_dir, filename)
     if not os.path.exists(cache_path):
@@ -86,6 +89,10 @@ def cached_path(url_or_filename, cache_dir=None):
     """
     if cache_dir is None:
         cache_dir = PYTORCH_PRETRAINED_BERT_CACHE
+    if sys.version_info[0] == 3 and isinstance(url_or_filename, Path):
+        url_or_filename = str(url_or_filename)
+    if sys.version_info[0] == 3 and isinstance(cache_dir, Path):
+        cache_dir = str(cache_dir)
 
     parsed = urlparse(url_or_filename)
 
@@ -171,6 +178,8 @@ def get_from_cache(url, cache_dir=None):
     """
     if cache_dir is None:
         cache_dir = PYTORCH_PRETRAINED_BERT_CACHE
+    if sys.version_info[0] == 3 and isinstance(cache_dir, Path):
+        cache_dir = str(cache_dir)
 
     if not os.path.exists(cache_dir):
         os.makedirs(cache_dir)