diff --git a/uploader.py b/uploader.py
index 9d6f25e..b099966 100644
--- a/uploader.py
+++ b/uploader.py
@@ -121,7 +121,7 @@ class CalibreClient:
                 except requests.HTTPError as e:
                     last_err = e
                     if resp.status_code in (502, 503, 504) and attempt < 3:
-                        delay = 2 if attempt == 1 else 6
+                        delay = 4 if attempt == 1 else 12
                         log.warning("HTTP %s on attempt %d/3 — retrying in %ds ...", resp.status_code, attempt, delay)
                         time.sleep(delay)
                         continue