diff --git a/harbor/logbook_auto.py b/harbor/logbook_auto.py
index 7fefb45..00d1c33 100644
--- a/harbor/logbook_auto.py
+++ b/harbor/logbook_auto.py
@@ -13,6 +13,7 @@ Milestones and narrative entries stay with people: they need judgement.
 
 State (the last commit seen) is kept in the logbook folder as auto.json."""
 import json
+import os
 import re
 import subprocess
 import sys
@@ -81,7 +82,9 @@ def log_commits(project, repo, since, head):
 def rebuild_stats(project, repo, stats_repo, head):
     """Run the open-seas progress tools on the scratch copy and store their statistics and chart."""
     tools = Path(stats_repo) / "tools" / "progress"
-    run = lambda *argv: subprocess.run([sys.executable, "-B", *map(str, argv)], cwd=str(stats_repo),
+    # its own data dir: the agents' compiles hold the shared decomp-build\pirates.h open
+    env = dict(os.environ, OPENSEAS_DATA=os.environ.get("HARBOR_LOGBOOK_DATA", r"R:\Workspace\Data\openseas-logbook"))
+    run = lambda *argv: subprocess.run([sys.executable, "-B", *map(str, argv)], cwd=str(stats_repo), env=env,
                                        capture_output=True, text=True, encoding="utf-8", errors="replace", timeout=900)
     sync = run(tools / "sync_decomp.py", "--decomp", repo)
     if sync.returncode != 0: