diff --git a/bergson/data.py b/bergson/data.py
index 4475585..3f8b65e 100644
--- a/bergson/data.py
+++ b/bergson/data.py
@@ -1,6 +1,7 @@
 import json
 import math
 import os
+import random
 from dataclasses import dataclass
 from pathlib import Path
 from typing import Literal, Sequence
@@ -114,7 +115,7 @@ def ceildiv(a: int, b: int) -> int:
     return -(-a // b)  # Equivalent to math.ceil(a / b) but faster for integers
 
 
-def allocate_batches(doc_lengths: list[int], N: int) -> list[list[int]]:
+def allocate_batches(doc_lengths: list[int], N: int, seed: int = 42) -> list[list[int]]:
     """
     Allocate documents into batches that are then distributed evenly across
     a fixed number of workers.
@@ -230,8 +231,13 @@ def allocate_batches(doc_lengths: list[int], N: int) -> list[list[int]]:
     for b_idx, batch in enumerate(batches):
         allocation[b_idx % world_size].append(batch)
 
-    # sanity: equal # of batches per worker
+    # Sanity: equal # of batches per worker
     assert len({len(b) for b in allocation}) == 1
+
+    # Break any systematic ordering of batches
+    random.seed(seed)
+    random.shuffle(allocation[rank])
+
     return allocation[rank]