diff --git a/bson/objectid.py b/bson/objectid.py
index fc00ccebb..ea765c830 100644
--- a/bson/objectid.py
+++ b/bson/objectid.py
@@ -140,6 +140,9 @@ class ObjectId(object):
 
         .. versionadded:: 2.3
         """
+        if not oid:
+            return False
+
         try:
             ObjectId(oid)
             return True
diff --git a/test/test_objectid.py b/test/test_objectid.py
index dc33366b2..d7b950542 100644
--- a/test/test_objectid.py
+++ b/test/test_objectid.py
@@ -181,6 +181,7 @@ class TestObjectId(unittest.TestCase):
         self.assertEqual(oid_1_9, oid_1_10)
 
     def test_is_valid(self):
+        self.assertFalse(ObjectId.is_valid(None))
         self.assertFalse(ObjectId.is_valid(4))
         self.assertFalse(ObjectId.is_valid(175.0))
         self.assertFalse(ObjectId.is_valid({"test": 4}))