diff --git a/pgcommitfest/commitfest/ajax.py b/pgcommitfest/commitfest/ajax.py
index 8137dfdf..1592e800 100644
--- a/pgcommitfest/commitfest/ajax.py
+++ b/pgcommitfest/commitfest/ajax.py
@@ -87,13 +87,19 @@ def getThreads(request):
     else:
         attachonly = 0
 
-    # Make a JSON api call to the archives server
+    # Make a JSON api call to the archives server for each list. A message
+    # that was sent to more than one list is only returned once.
     params = {"n": 100, "a": attachonly}
     if search:
         params["s"] = search
 
-    r = _archivesAPI("/list/pgsql-hackers/latest.json", params)
-    return sorted(r, key=lambda x: x["date"], reverse=True)
+    messages = {}
+    for listname in ("pgsql-hackers", "pgsql-bugs"):
+        for m in _archivesAPI("/list/%s/latest.json" % listname, params):
+            messages.setdefault(m["msgid"], m)
+
+    r = sorted(messages.values(), key=lambda x: x["date"], reverse=True)
+    return r[: params["n"]]
 
 
 def getMessages(request):
diff --git a/pgcommitfest/commitfest/tests/test_get_threads.py b/pgcommitfest/commitfest/tests/test_get_threads.py
new file mode 100644
index 00000000..6ca209d6
--- /dev/null
+++ b/pgcommitfest/commitfest/tests/test_get_threads.py
@@ -0,0 +1,38 @@
+from django.test import RequestFactory
+
+from unittest.mock import patch
+
+from pgcommitfest.commitfest.ajax import getThreads
+
+
+def _msg(msgid, date):
+    return {"msgid": msgid, "date": date, "from": "a@example.com", "subj": msgid}
+
+
+def test_get_threads_searches_hackers_and_bugs():
+    hackers = [
+        _msg("h%d" % i, "2026-01-01T%02d:%02d:00" % (i // 60, i % 60))
+        for i in range(100)
+    ]
+    # b1 is newer than everything on hackers, h99 was sent to both lists
+    bugs = [_msg("b1", "2026-01-02T00:00:00"), hackers[99]]
+
+    def fake(suburl, params=None):
+        return {
+            "/list/pgsql-hackers/latest.json": hackers,
+            "/list/pgsql-bugs/latest.json": bugs,
+        }[suburl]
+
+    request = RequestFactory().get("/ajax/getThreads/", {"s": "x", "a": "1"})
+    with patch("pgcommitfest.commitfest.ajax._archivesAPI", side_effect=fake) as api:
+        result = getThreads(request)
+
+    assert [c.args for c in api.call_args_list] == [
+        ("/list/pgsql-hackers/latest.json", {"n": 100, "a": 1, "s": "x"}),
+        ("/list/pgsql-bugs/latest.json", {"n": 100, "a": 1, "s": "x"}),
+    ]
+    # Merged newest first, h99 deduplicated, and capped at 100 so the oldest
+    # message (h0) is dropped.
+    assert [m["msgid"] for m in result] == ["b1"] + [
+        "h%d" % i for i in range(99, 0, -1)
+    ]