diff --git a/django_q/brokers/__init__.py b/django_q/brokers/__init__.py
index a8380ee..0d10cac 100644
--- a/django_q/brokers/__init__.py
+++ b/django_q/brokers/__init__.py
@@ -29,6 +29,11 @@ class Broker(object):
         """
         pass
 
+    def lock_size(self):
+        """
+        :return: the number of tasks currently awaiting acknowledgement
+        """
+
     def delete_queue(self):
         """
         Deletes the queue from the broker
diff --git a/django_q/monitor.py b/django_q/monitor.py
index 3671e83..6a3bcf4 100644
--- a/django_q/monitor.py
+++ b/django_q/monitor.py
@@ -83,8 +83,9 @@ def monitor(run_once=False, broker=None):
             # bottom bar
             i += 1
             queue_size = broker.queue_size()
-            if hasattr(broker, 'lock_size'):
-                queue_size = '{}({})'.format(queue_size, broker.lock_size())
+            lock_size = broker.lock_size()
+            if lock_size:
+                queue_size = '{}({})'.format(queue_size, lock_size)
             print(term.move(i, 0) + term.white_on_cyan(term.center(broker.info(), width=col_width * 2)))
             print(term.move(i, 2 * col_width) + term.black_on_cyan(term.center(_('Queued'), width=col_width)))
             print(term.move(i, 3 * col_width) + term.white_on_cyan(term.center(queue_size, width=col_width)))
diff --git a/django_q/tests/test_brokers.py b/django_q/tests/test_brokers.py
index 150adfd..59514cc 100644
--- a/django_q/tests/test_brokers.py
+++ b/django_q/tests/test_brokers.py
@@ -12,6 +12,7 @@ def test_broker():
     broker.enqueue('test')
     broker.dequeue()
     broker.queue_size()
+    broker.lock_size()
     broker.purge_queue()
     broker.delete('id')
     broker.delete_queue()
diff --git a/django_q/tests/test_monitor.py b/django_q/tests/test_monitor.py
index 69d9af5..2c73723 100644
--- a/django_q/tests/test_monitor.py
+++ b/django_q/tests/test_monitor.py
@@ -1,6 +1,6 @@
 import pytest
 
-from django_q import async
+from django_q import async, get_broker
 from django_q.cluster import Cluster
 from django_q.monitor import monitor, info
 from django_q.status import Stat
@@ -23,9 +23,14 @@ def test_monitor():
             assert stat.empty_queues() is True
             break
     assert found_c is True
-    # test lock size for orm broker
+    # test lock size
     Conf.ORM = 'default'
-    monitor(run_once=True)
+    b = get_broker('monitor_test')
+    b.enqueue('test')
+    b.dequeue()
+    assert b.lock_size() == 1
+    monitor(run_once=True, broker=b)
+    b.delete_queue()
     Conf.ORM = None