Cleanup after v0.3.0 release
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9e6c15f..eb43d7d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,4 @@
+## 0.4.0 (Unreleased)
 ## 0.3.0 (May 29, 2019)
 
 NOTES: