diff --git a/kikuchipy/release.py b/kikuchipy/release.py
index 2c9ea81c..efb7607a 100644
--- a/kikuchipy/release.py
+++ b/kikuchipy/release.py
@@ -34,4 +34,4 @@
 name = "kikuchipy"
 platforms = ["Linux", "MacOS X", "Windows"]
 status = "Development"
-version = "0.3.1"
+version = "0.4.0dev"