diff --git a/shotgun_api3/shotgun.py b/shotgun_api3/shotgun.py
index f11f895d..47268733 100644
--- a/shotgun_api3/shotgun.py
+++ b/shotgun_api3/shotgun.py
@@ -2426,7 +2426,12 @@ def _upload_to_storage(self, entity_type, entity_id, path, field_name, display_n
 
         is_multipart_upload = (os.path.getsize(path) > self._MULTIPART_UPLOAD_CHUNK_SIZE)
 
-        upload_info = self._get_attachment_upload_info(is_thumbnail, filename, is_multipart_upload)
+        # Step 1b: quote filename
+        # To avoid the filename turning into garbled text,
+        # quote filename using urllib.parse.quote("<filename_encoding_utf8>")
+        filename = filename.encode("utf8")
+        quote_filename = urllib.parse.quote(filename)
+        upload_info = self._get_attachment_upload_info(is_thumbnail, quote_filename, is_multipart_upload)
 
         # Step 2: upload the file
         # We upload large files in multiple parts because it is more robust