diff --git a/py25/bacpypes/object.py b/py25/bacpypes/object.py
index c34ccd5..db427d5 100755
--- a/py25/bacpypes/object.py
+++ b/py25/bacpypes/object.py
@@ -1351,6 +1351,7 @@ class DeviceObject(Object):
         , OptionalProperty('timeSynchronizationInterval', Unsigned)
         , OptionalProperty('alignIntervals', Boolean)
         , OptionalProperty('intervalOffset', Unsigned)
+        , OptionalProperty('serialNumber', CharacterString)
         ]
 
 register_object_type(DeviceObject)
diff --git a/py27/bacpypes/object.py b/py27/bacpypes/object.py
index 1b4bd0a..5248d0c 100755
--- a/py27/bacpypes/object.py
+++ b/py27/bacpypes/object.py
@@ -1334,6 +1334,7 @@ class DeviceObject(Object):
         , OptionalProperty('timeSynchronizationInterval', Unsigned)
         , OptionalProperty('alignIntervals', Boolean)
         , OptionalProperty('intervalOffset', Unsigned)
+        , OptionalProperty('serialNumber', CharacterString)
         ]
 
 @register_object_type
diff --git a/py34/bacpypes/object.py b/py34/bacpypes/object.py
index f983c3b..982f982 100755
--- a/py34/bacpypes/object.py
+++ b/py34/bacpypes/object.py
@@ -1334,6 +1334,7 @@ class DeviceObject(Object):
         , OptionalProperty('timeSynchronizationInterval', Unsigned)
         , OptionalProperty('alignIntervals', Boolean)
         , OptionalProperty('intervalOffset', Unsigned)
+        , OptionalProperty('serialNumber', CharacterString)
         ]
 
 @register_object_type