diff --git a/CHANGELOG.md b/CHANGELOG.md
index df384d1..8c44561 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,11 @@
+## v0.5.0 2016-08-21
+
+### Added
+
+* Allow `optional` attribute to be left undefined (@nepalez)
+
+[Compare v0.4.0...v0.5.0](https://github.com/dry-rb/dry-initializer/compare/v0.4.0..v0.5.0)
+
 ## v0.4.0 2016-05-28
 
 ### Deleted (backward-incompatible changes)
diff --git a/dry-initializer.gemspec b/dry-initializer.gemspec
index 6456121..3853322 100644
--- a/dry-initializer.gemspec
+++ b/dry-initializer.gemspec
@@ -1,6 +1,6 @@
 Gem::Specification.new do |gem|
   gem.name     = "dry-initializer"
-  gem.version  = "0.4.0"
+  gem.version  = "0.5.0"
   gem.author   = ["Vladimir Kochnev (marshall-lee)", "Andrew Kozin (nepalez)"]
   gem.email    = ["hashtable@yandex.ru", "andrew.kozin@gmail.com"]
   gem.homepage = "https://github.com/dryrb/dry-initializer"