diff --git a/siuba/__init__.py b/siuba/__init__.py
index 3ab55dd2..5f3872e1 100644
--- a/siuba/__init__.py
+++ b/siuba/__init__.py
@@ -1,5 +1,5 @@
 # version ---------------------------------------------------------------------
-__version__ = "0.3.0"
+__version__ = "0.4.0rc1"
 
 # default imports--------------------------------------------------------------
 from .siu import _, Fx, Lam