diff --git a/zerver/lib/upload.py b/zerver/lib/upload.py
index 7f1978183c..16060b5a0d 100644
--- a/zerver/lib/upload.py
+++ b/zerver/lib/upload.py
@@ -11,7 +11,7 @@ import unicodedata
 
 from zerver.lib.avatar_hash import user_avatar_path
 from zerver.lib.exceptions import JsonableError, ErrorCode
-from zerver.lib.str_utils import NonBinaryStr, force_bytes
+from zerver.lib.str_utils import NonBinaryStr
 
 from boto.s3.bucket import Bucket
 from boto.s3.key import Key
@@ -355,9 +355,9 @@ class S3UploadBackend(ZulipUploadBackend):
         conn = S3Connection(settings.S3_KEY, settings.S3_SECRET_KEY)
         bucket = get_bucket(conn, bucket_name)
         key = bucket.get_key(file_path)
-        image_data = force_bytes(key.get_contents_as_string())
+        image_data = key.get_contents_as_string()
 
-        resized_medium = resize_avatar(image_data, MEDIUM_AVATAR_SIZE)
+        resized_medium = resize_avatar(image_data, MEDIUM_AVATAR_SIZE)  # type: ignore # image_data is `bytes`, boto subs are wrong
         upload_image_to_s3(
             bucket_name,
             s3_file_name + "-medium.png",