diff --git a/src/wormhole/server/rendezvous.py b/src/wormhole/server/rendezvous.py
index 8633df9..db215d7 100644
--- a/src/wormhole/server/rendezvous.py
+++ b/src/wormhole/server/rendezvous.py
@@ -534,7 +534,7 @@ class Rendezvous(service.MultiService):
         service.MultiService.__init__(self)
         self._db = db
         self._welcome = welcome
-        self._blur_usage = None
+        self._blur_usage = blur_usage
         log_requests = blur_usage is None
         self._log_requests = log_requests
         self._apps = {}
diff --git a/src/wormhole/test/test_server.py b/src/wormhole/test/test_server.py
index 7e6238a..b8e3009 100644
--- a/src/wormhole/test/test_server.py
+++ b/src/wormhole/test/test_server.py
@@ -953,6 +953,40 @@ class Summary(unittest.TestCase):
         self.assertEqual(summ(2, second=3, pruned=True),
                          Usage(1, 2, 4, u"pruney"))
 
+    def test_blur(self):
+        db = get_db(":memory:")
+        rv = rendezvous.Rendezvous(db, None, 3600)
+        APPID = u"appid"
+        app = rv.get_app(APPID)
+        app.claim_nameplate(u"npid", u"side1", 10) # start time is 10
+        rv.prune(now=123, old=50)
+        # start time should be rounded to top of the hour (blur_usage=3600)
+        row = db.execute("SELECT * FROM `nameplate_usage`").fetchone()
+        self.assertEqual(row["started"], 0)
+
+        app = rv.get_app(APPID)
+        app.open_mailbox(u"mbid", u"side1", 20) # start time is 20
+        rv.prune(now=123, old=50)
+        row = db.execute("SELECT * FROM `mailbox_usage`").fetchone()
+        self.assertEqual(row["started"], 0)
+
+    def test_no_blur(self):
+        db = get_db(":memory:")
+        rv = rendezvous.Rendezvous(db, None, None)
+        APPID = u"appid"
+        app = rv.get_app(APPID)
+        app.claim_nameplate(u"npid", u"side1", 10) # start time is 10
+        rv.prune(now=123, old=50)
+        row = db.execute("SELECT * FROM `nameplate_usage`").fetchone()
+        self.assertEqual(row["started"], 10)
+
+        app = rv.get_app(APPID)
+        app.open_mailbox(u"mbid", u"side1", 20) # start time is 20
+        rv.prune(now=123, old=50)
+        row = db.execute("SELECT * FROM `mailbox_usage`").fetchone()
+        self.assertEqual(row["started"], 20)
+
+
 class Accumulator(protocol.Protocol):
     def __init__(self):
         self.data = b""