diff --git a/firebase_admin/firestore.py b/firebase_admin/firestore.py
index 32c9897d5..224ba3aeb 100644
--- a/firebase_admin/firestore.py
+++ b/firebase_admin/firestore.py
@@ -34,7 +34,7 @@
 _FIRESTORE_ATTRIBUTE = '_firestore'
 
 
-def client(app=None):
+def client(app=None) -> firestore.Client:
     """Returns a client that can be used to interact with Google Cloud Firestore.
 
     Args: