diff --git a/drain/drain.sh b/drain/drain.sh
index 23ef9d6..71f53bf 100755
--- a/drain/drain.sh
+++ b/drain/drain.sh
@@ -16,12 +16,17 @@ touch done.txt
 
 idx_of() { python3 -c 'import sys;print(int(sys.argv[1][4:14],36))' "$(basename "$1" .jss)"; }
 
-put() { # key file
-  local code
-  code=$(curl -sS -m 600 -o /tmp/drain.put.json -w "%{http_code}" -X PUT "$STRATA_URL/archive/$1" \
-    -H "Authorization: Bearer $STRATA_INGEST_TOKEN" -H "Content-Type: application/octet-stream" \
-    -A "strata-drain/1" --data-binary "@$2")
-  [ "$code" = "200" ] || { echo "PUT $1 -> $code $(cat /tmp/drain.put.json)" >&2; return 1; }
+put() { # key file — retries a 5xx (R2 hiccup, worker exception) three times with backoff
+  local code attempt
+  for attempt in 1 2 3 4; do
+    code=$(curl -sS -m 600 -o /tmp/drain.put.json -w "%{http_code}" -X PUT "$STRATA_URL/archive/$1" \
+      -H "Authorization: Bearer $STRATA_INGEST_TOKEN" -H "Content-Type: application/octet-stream" \
+      -A "strata-drain/1" --data-binary "@$2" || echo 000)
+    [ "$code" = "200" ] && return 0
+    echo "PUT $1 -> $code $(head -c 200 /tmp/drain.put.json) (attempt $attempt)" >&2
+    case "$code" in 5*|000) sleep $((attempt * attempt * 5));; *) return 1;; esac
+  done
+  return 1
 }
 
 mapfile -t all < <(ls "$SEGMENTS"/seg_*.jss | sort)