diff --git a/cubicweb_s3storage/storages.py b/cubicweb_s3storage/storages.py
index 2dd30b8ecf852ca0f64e775b04496cbb0399b4b7_Y3ViaWN3ZWJfczNzdG9yYWdlL3N0b3JhZ2VzLnB5..3a2b326e89cc19dadfab6f6131c066f2565f9a53_Y3ViaWN3ZWJfczNzdG9yYWdlL3N0b3JhZ2VzLnB5 100644
--- a/cubicweb_s3storage/storages.py
+++ b/cubicweb_s3storage/storages.py
@@ -102,8 +102,11 @@
             else:
                 upload_key = key
             extra_args = self.get_upload_extra_args(entity, attr, key)
-            self.s3cnx.upload_fileobj(buffer, self.bucket, upload_key,
-                                      ExtraArgs=extra_args)
+
+            s3_object = self.bucket.put_object(
+                    Body=buffer,
+                    Key=upload_key,
+                    **extra_args)
             buffer.close()
 
             # when key is suffixed, move to final key in post commit event