diff --git a/.bumpversion.cfg b/.bumpversion.cfg
index 7b2dfe10..2c9f6b88 100644
--- a/.bumpversion.cfg
+++ b/.bumpversion.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 0.4.3.dev0
+current_version = 0.5.0.dev0
 commit = True
 tag = True
 sign_tags = True
diff --git a/setup.py b/setup.py
index 548f557e..b4a6f824 100644
--- a/setup.py
+++ b/setup.py
@@ -28,7 +28,7 @@ def read(fname):
 
 setup(
     name="ome-zarr",
-    version="0.4.3.dev0",
+    version="0.5.0.dev0",
     author="The Open Microscopy Team",
     url="https://github.com/ome/ome-zarr-py",
     description="Implementation of images in Zarr files.",