diff --git a/brozzler/worker.py b/brozzler/worker.py
index 5dbb330..d47f939 100644
--- a/brozzler/worker.py
+++ b/brozzler/worker.py
@@ -113,7 +113,11 @@ class YoutubeDLSpy(urllib.request.BaseHandler):
 class BrozzlerWorker:
     logger = logging.getLogger(__module__ + "." + __qualname__)
 
-    HEARTBEAT_INTERVAL = 20.0
+    # 3⅓ min heartbeat interval => 10 min ttl
+    # This is kind of a long time, because `frontier.claim_sites()`, which runs
+    # in the same thread as the heartbeats, can take a while on a busy brozzler
+    # cluster with slow rethinkdb.
+    HEARTBEAT_INTERVAL = 200.0
     SITE_SESSION_MINUTES = 15
 
     def __init__(
diff --git a/setup.py b/setup.py
index f49c9e6..659ce46 100644
--- a/setup.py
+++ b/setup.py
@@ -32,7 +32,7 @@ def find_package_data(package):
 
 setuptools.setup(
         name='brozzler',
-        version='1.4.dev294',
+        version='1.4.dev295',
         description='Distributed web crawling with browsers',
         url='https://github.com/internetarchive/brozzler',
         author='Noah Levitt',