diff --git a/s3fs/core.py b/s3fs/core.py
index 11053005..b4ab8a93 100644
--- a/s3fs/core.py
+++ b/s3fs/core.py
@@ -1153,7 +1153,7 @@ async def _put_file(
         callback.set_size(size)
 
         if "ContentType" not in kwargs:
-            content_type, _ = mimetypes.guess_type(lpath)
+            content_type = mimetypes.guess_type(rpath)[0] or mimetypes.guess_type(lpath)[0]
             if content_type is not None:
                 kwargs["ContentType"] = content_type