diff --git a/pymongo/_version.py b/pymongo/_version.py
index aa1e4a883f..caaab856b1 100644
--- a/pymongo/_version.py
+++ b/pymongo/_version.py
@@ -19,7 +19,7 @@
 import re
 from typing import Union
 
-__version__ = "4.19.0"
+__version__ = "4.20.0.dev0"
 
 
 def get_version_tuple(version: str) -> tuple[Union[int, str], ...]: