diff --git a/google/cloud/firestore_v1/collection.py b/google/cloud/firestore_v1/collection.py
index 165e0dfb3..23e051895 100644
--- a/google/cloud/firestore_v1/collection.py
+++ b/google/cloud/firestore_v1/collection.py
@@ -446,7 +446,7 @@ def on_snapshot(self, callback):
             db = firestore_v1.Client()
             collection_ref = db.collection(u'users')
 
-            def on_snapshot(collection_snapshot):
+            def on_snapshot(collection_snapshot, changes, read_time):
                 for doc in collection_snapshot.documents:
                     print(u'{} => {}'.format(doc.id, doc.to_dict()))
 
diff --git a/google/cloud/firestore_v1/document.py b/google/cloud/firestore_v1/document.py
index df2861c15..571315e87 100644
--- a/google/cloud/firestore_v1/document.py
+++ b/google/cloud/firestore_v1/document.py
@@ -512,7 +512,7 @@ def on_snapshot(self, callback):
             db = firestore_v1.Client()
             collection_ref = db.collection(u'users')
 
-            def on_snapshot(document_snapshot):
+            def on_snapshot(document_snapshot, changes, read_time):
                 doc = document_snapshot
                 print(u'{} => {}'.format(doc.id, doc.to_dict()))