diff --git a/README.md b/README.md
index 0b813b6..adfc09d 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,9 @@
 
 **Heta** is a modeling language for quantitative systems pharmacology and systems biology.
 
-Seea also the [Heta tutorial](https://hetalang.github.io/#/resources/?id=lesson-0-introduction)
+The current version is **0.4.0**.
+
+Sea also the [Heta tutorial](https://hetalang.github.io/#/resources/?id=lesson-0-introduction)
 
 ## Language specification
 
@@ -118,8 +120,6 @@ Heta language was originally developed for internal projects of InSysBio to supp
 
 ## Versions
 
-The current version is **0.4.0**.
-
 The **latest** version of Heta standard is located in **master** branch of the [hetalang/heta-specifications](https://github.com/hetalang/heta-specifications) repository. 
 
 The previous versions are stored as **tags** in the repository.
diff --git a/changelog.md b/changelog.md
index 2d14f0e..516acdf 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,10 @@
 # Change Log
 
+## 0.4.0
+
+- `reversible` property for `@Process`
+- substitute `#include @UnitDef` instance by `#defineUnit` action
+
 ## 0.3.4
 
 - include `atStart` in _Switcher class