diff --git a/scripts/estimate-nl-users.py b/scripts/estimate-nl-users.py
index 4ae5e11..1a6ae8f 100644
--- a/scripts/estimate-nl-users.py
+++ b/scripts/estimate-nl-users.py
@@ -116,11 +116,22 @@ DURATION, OUT, LANGS, AUTHOR_LANGS = parse_args(sys.argv[1:])
 FOREVER = DURATION <= 0  # 0 (or negative) = run indefinitely
 
 
+# urllib announces itself as "Python-urllib/3.x", which bsky-search.jazco.io rejects with
+# a 403. That silently nulled bluesky_total_users -- the extrapolation anchor -- from at
+# least 2026-08-30 until it was caught on 2026-09-02. Always send a real User-Agent.
+USER_AGENT = "atproto.nl-stats/1.0 (+https://atproto.nl)"
+
+
+def fetch_json(url, timeout=20):
+    req = urllib.request.Request(url, headers={"User-Agent": USER_AGENT})
+    with urllib.request.urlopen(req, timeout=timeout) as r:
+        return json.load(r)
+
+
 def bluesky_total():
     """Current Bluesky account total (extrapolation anchor)."""
     try:
-        with urllib.request.urlopen("https://bsky-search.jazco.io/stats", timeout=20) as r:
-            return json.load(r).get("total_users")
+        return fetch_json("https://bsky-search.jazco.io/stats").get("total_users")
     except Exception as e:
         print(f"  bluesky total fetch failed: {e}", file=sys.stderr)
         return None
@@ -135,8 +146,7 @@ def resolve_handles(dids):
         batch = dids[i:i + 25]
         qs = "&".join("actors=" + urllib.parse.quote(d) for d in batch)
         try:
-            with urllib.request.urlopen(f"{base}?{qs}", timeout=20) as r:
-                data = json.load(r)
+            data = fetch_json(f"{base}?{qs}")
             for p in data.get("profiles", []):
                 handles[p["did"]] = p.get("handle", "")
         except Exception as e: