diff --git a/alarmdecoder/zonetracking.py b/alarmdecoder/zonetracking.py
index 13be3c3..ae92eb7 100644
--- a/alarmdecoder/zonetracking.py
+++ b/alarmdecoder/zonetracking.py
@@ -189,7 +189,7 @@ def update(self, message):
                     if match is None:
                         return
 
-                    zone = match.group(1)
+                    zone = int(match.group(1))
 
                 # Add new zones and clear expired ones.
                 if zone in self._zones_faulted:
diff --git a/test/test_zonetracking.py b/test/test_zonetracking.py
index 6d8f087..0156871 100644
--- a/test/test_zonetracking.py
+++ b/test/test_zonetracking.py
@@ -76,7 +76,7 @@ def test_ECP_failure(self):
         msg = Message('[00000000000000100A--],0bf,[f707000600e5800c0c020000],"CHECK 1                         "')
         self._zonetracker.update(msg)
 
-        self.assertEqual(self._zonetracker._zones['1'].status, Zone.CHECK)
+        self.assertEqual(self._zonetracker._zones[1].status, Zone.CHECK)
 
     def test_zone_restore_skip(self):
         panel_messages = [