diff --git a/lib/iris/__init__.py b/lib/iris/__init__.py
index 26f03c0566..713c163deb 100644
--- a/lib/iris/__init__.py
+++ b/lib/iris/__init__.py
@@ -104,7 +104,7 @@ def callback(cube, field, filename):
 
 
 # Iris revision.
-__version__ = "3.2.dev0"
+__version__ = "3.3.dev0"
 
 # Restrict the names imported when using "from iris import *"
 __all__ = [