diff --git a/notebook/_version.py b/notebook/_version.py
index 7b3856f247..6c5729f54d 100644
--- a/notebook/_version.py
+++ b/notebook/_version.py
@@ -5,7 +5,7 @@
 import re
 
 # Version string must appear intact for tbump versioning
-__version__ = '6.4.8'
+__version__ = '6.5.0.dev0'
 
 # Build up version_info tuple for backwards compatibility
 pattern = r'(?P<major>\d+).(?P<minor>\d+).(?P<patch>\d+)(?P<rest>.*)'
diff --git a/pyproject.toml b/pyproject.toml
index e0cf10c67c..9553029ced 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,7 +17,7 @@ before-build-python = ["pip install babel", "npm install -g po2json"]
 ignore-glob = ["docs/source/examples/Notebook/Working With Markdown Cells.ipynb", "docs-translations/**/README.md", "docs/source/contributing.rst", "docs/source/examples/Notebook/JavaScript Notebook Extensions.ipynb", "CHANGELOG.md", "notebook/static/components/**/*.*"]
 
 [tool.tbump.version]
-current = "6.4.8"
+current = "6.5.0.dev0"
 regex = '''
   (?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)
   ((?P<channel>a|b|rc|.dev)(?P<release>\d+))?