diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6027dfa..7672fa1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,14 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## 0.5.0 - 2020-01-29
+
+### Added
+
+ - Ability to specify aggregation policy for metrics collected from multiple process and exposed via single endpoint. [@Envek]
+
+   For now it is only used by yabeda-prometheus when official Prometheus client is configured to use file storage for metrics.
+
 ## 0.4.0 - 2020-01-28
 
 ### Changed
diff --git a/lib/yabeda/metric.rb b/lib/yabeda/metric.rb
index 0771f4a..7a2b32b 100644
--- a/lib/yabeda/metric.rb
+++ b/lib/yabeda/metric.rb
@@ -13,6 +13,7 @@ class Metric
     option :unit,    optional: true, comment: "In which units it is measured. E.g. `seconds`"
     option :per,     optional: true, comment: "Per which unit is measured `unit`. E.g. `call` as in seconds per call"
     option :group,   optional: true, comment: "Category name for grouping metrics"
+    option :aggregation, optional: true, comment: "How adapters should aggregate values from different processes"
 
     # Returns the value for the given label set
     def get(labels = {})
diff --git a/lib/yabeda/version.rb b/lib/yabeda/version.rb
index a4b0dea..c2c2abb 100644
--- a/lib/yabeda/version.rb
+++ b/lib/yabeda/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module Yabeda
-  VERSION = "0.4.0"
+  VERSION = "0.5.0"
 end