diff --git a/lib/CHANGELOG.md b/lib/CHANGELOG.md
index ebff5f2..98ec6c4 100644
--- a/lib/CHANGELOG.md
+++ b/lib/CHANGELOG.md
@@ -2,24 +2,24 @@
 
 ## [1.2.8](https://github.com/skywinder/Github-Changelog-Generator/tree/1.2.8)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.2.7...1.2.8)
-#### 17/02/15
+#### 2015-02-17
 - *Merged pull-request:* Feature/fix 37 [\#49](https://github.com/skywinder/Github-Changelog-Generator/pull/49) ([skywinder](https://github.com/skywinder))
 
 - *Closed issue:* Bugs, that closed simultaneously with push not appeared in correct version. [\#37](https://github.com/skywinder/Github-Changelog-Generator/issues/37)
 
 ## [1.2.7](https://github.com/skywinder/Github-Changelog-Generator/tree/1.2.7)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.2.6...1.2.7)
-#### 26/01/15
+#### 2015-01-26
 - *Merged pull-request:* Add compare link between older version and newer version [\#46](https://github.com/skywinder/Github-Changelog-Generator/pull/46) ([sue445](https://github.com/sue445))
 
 ## [1.2.6](https://github.com/skywinder/Github-Changelog-Generator/tree/1.2.6)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.2.5...1.2.6)
-#### 21/01/15
+#### 2015-01-21
 - *Merged pull-request:* fix link tag format [\#45](https://github.com/skywinder/Github-Changelog-Generator/pull/45) ([sugamasao](https://github.com/sugamasao))
 
 ## [1.2.5](https://github.com/skywinder/Github-Changelog-Generator/tree/1.2.5)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.2.4...1.2.5)
-#### 15/01/15
+#### 2015-01-15
 - *Merged pull-request:* PrettyPrint class is included using lowercase 'pp' [\#43](https://github.com/skywinder/Github-Changelog-Generator/pull/43) ([schwing](https://github.com/schwing))
 
 - *Merged pull-request:* support enterprise github via command line options [\#42](https://github.com/skywinder/Github-Changelog-Generator/pull/42) ([glenlovett](https://github.com/glenlovett))
@@ -30,16 +30,16 @@
 
 ## [1.2.4](https://github.com/skywinder/Github-Changelog-Generator/tree/1.2.4)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.2.3...1.2.4)
-#### 16/12/14
+#### 2014-12-16
 - *Merged pull-request:* Implement async fetching [\#39](https://github.com/skywinder/Github-Changelog-Generator/pull/39) ([skywinder](https://github.com/skywinder))
 
-- *Implemented enhancement:* Add ability to run with one parameter instead -u -p [\#38](https://github.com/skywinder/Github-Changelog-Generator/issues/38)
-
 - *Fixed bug:* Crash when try generate log for rails [\#35](https://github.com/skywinder/Github-Changelog-Generator/issues/35)
 
+- *Fixed bug:* Sometimes user is NULL during merges [\#41](https://github.com/skywinder/Github-Changelog-Generator/issues/41)
+
 ## [1.2.3](https://github.com/skywinder/Github-Changelog-Generator/tree/1.2.3)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.2.2...1.2.3)
-#### 16/12/14
+#### 2014-12-16
 - *Merged pull-request:* Fix crash when user is NULL [\#40](https://github.com/skywinder/Github-Changelog-Generator/pull/40) ([skywinder](https://github.com/skywinder))
 
 - *Implemented enhancement:* Add ability to run with one parameter instead -u -p [\#38](https://github.com/skywinder/Github-Changelog-Generator/issues/38)
@@ -50,14 +50,14 @@
 
 ## [1.2.2](https://github.com/skywinder/Github-Changelog-Generator/tree/1.2.2)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.2.1...1.2.2)
-#### 10/12/14
+#### 2014-12-10
 - *Merged pull-request:* Add a Bitdeli Badge to README [\#36](https://github.com/skywinder/Github-Changelog-Generator/pull/36) ([bitdeli-chef](https://github.com/bitdeli-chef))
 
 - *Fixed bug:* Encapsulate \[ \> \* \_ \ \] signs in issues names [\#34](https://github.com/skywinder/Github-Changelog-Generator/issues/34)
 
 ## [1.2.1](https://github.com/skywinder/Github-Changelog-Generator/tree/1.2.1)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.2.0...1.2.1)
-#### 22/11/14
+#### 2014-11-22
 - *Merged pull-request:* Issues for last tag not in list [\#29](https://github.com/skywinder/Github-Changelog-Generator/pull/29) ([skywinder](https://github.com/skywinder))
 
 - *Merged pull-request:* Disable default --filter-pull-requests option. [\#28](https://github.com/skywinder/Github-Changelog-Generator/pull/28) ([skywinder](https://github.com/skywinder))
@@ -66,7 +66,7 @@
 
 ## [1.2.0](https://github.com/skywinder/Github-Changelog-Generator/tree/1.2.0)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.1.4...1.2.0)
-#### 19/11/14
+#### 2014-11-19
 - *Merged pull-request:* Add filter for pull-requests labels. \(option --filter-pull-requests\) [\#27](https://github.com/skywinder/Github-Changelog-Generator/pull/27) ([skywinder](https://github.com/skywinder))
 
 - *Merged pull-request:* Test Pull-Request SHOULD NOT APPEAR IN LOG! [\#26](https://github.com/skywinder/Github-Changelog-Generator/pull/26) ([skywinder](https://github.com/skywinder))
@@ -77,21 +77,21 @@
 
 ## [1.1.4](https://github.com/skywinder/Github-Changelog-Generator/tree/1.1.4)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.1.2...1.1.4)
-#### 18/11/14
+#### 2014-11-18
 - *Merged pull-request:* Sort tags by date [\#23](https://github.com/skywinder/Github-Changelog-Generator/pull/23) ([skywinder](https://github.com/skywinder))
 
 - *Implemented enhancement:* Implement ability to retrieve GitHub token from ENV variable \(to not put it to script directly\) [\#19](https://github.com/skywinder/Github-Changelog-Generator/issues/19)
 
 ## [1.1.2](https://github.com/skywinder/Github-Changelog-Generator/tree/1.1.2)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.1.1...1.1.2)
-#### 12/11/14
+#### 2014-11-12
 - *Merged pull-request:* Fix bug with dot signs in project name [\#18](https://github.com/skywinder/Github-Changelog-Generator/pull/18) ([skywinder](https://github.com/skywinder))
 
 - *Merged pull-request:* Fix bug with dot signs in user name [\#17](https://github.com/skywinder/Github-Changelog-Generator/pull/17) ([skywinder](https://github.com/skywinder))
 
 ## [1.1.1](https://github.com/skywinder/Github-Changelog-Generator/tree/1.1.1)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.1.0...1.1.1)
-#### 10/11/14
+#### 2014-11-10
 - *Merged pull-request:* Remove duplicates of issues and pull-requests with same number [\#15](https://github.com/skywinder/Github-Changelog-Generator/pull/15) ([skywinder](https://github.com/skywinder))
 
 - *Merged pull-request:* Sort issues by tags [\#14](https://github.com/skywinder/Github-Changelog-Generator/pull/14) ([skywinder](https://github.com/skywinder))
@@ -100,7 +100,7 @@
 
 ## [1.1.0](https://github.com/skywinder/Github-Changelog-Generator/tree/1.1.0)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.0.1...1.1.0)
-#### 10/11/14
+#### 2014-11-10
 - *Implemented enhancement:* Detect username and project form origin [\#11](https://github.com/skywinder/Github-Changelog-Generator/issues/11)
 
 - *Fixed bug:* Markdown formating in the last line wrong [\#9](https://github.com/skywinder/Github-Changelog-Generator/issues/9)
@@ -109,14 +109,12 @@
 
 ## [1.0.1](https://github.com/skywinder/Github-Changelog-Generator/tree/1.0.1)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/1.0.0...1.0.1)
-#### 10/11/14
+#### 2014-11-10
 - *Merged pull-request:* Implement support of different tags. [\#8](https://github.com/skywinder/Github-Changelog-Generator/pull/8) ([skywinder](https://github.com/skywinder))
 
 ## [1.0.0](https://github.com/skywinder/Github-Changelog-Generator/tree/1.0.0)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/0.1.0...1.0.0)
-#### 07/11/14
-- *Merged pull-request:* Implement support of different tags. [\#8](https://github.com/skywinder/Github-Changelog-Generator/pull/8) ([skywinder](https://github.com/skywinder))
-
+#### 2014-11-07
 - *Merged pull-request:* Add support for issues in CHANGELOG [\#7](https://github.com/skywinder/Github-Changelog-Generator/pull/7) ([skywinder](https://github.com/skywinder))
 
 - *Merged pull-request:* Fix parsing date of pull request [\#3](https://github.com/skywinder/Github-Changelog-Generator/pull/3) ([skywinder](https://github.com/skywinder))
@@ -129,16 +127,16 @@
 
 ## [0.1.0](https://github.com/skywinder/Github-Changelog-Generator/tree/0.1.0)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/0.0.2...0.1.0)
-#### 07/11/14
+#### 2014-11-07
 - *Merged pull-request:* Add changelog generation for last tag [\#2](https://github.com/skywinder/Github-Changelog-Generator/pull/2) ([skywinder](https://github.com/skywinder))
 
 - *Merged pull-request:* Add option \(-o --output\) to specify name of the output file. [\#1](https://github.com/skywinder/Github-Changelog-Generator/pull/1) ([skywinder](https://github.com/skywinder))
 
 ## [0.0.2](https://github.com/skywinder/Github-Changelog-Generator/tree/0.0.2)
 [Full Changelog](https://github.com/skywinder/Github-Changelog-Generator/compare/0.0.1...0.0.2)
-#### 06/11/14
+#### 2014-11-06
 ## [0.0.1](https://github.com/skywinder/Github-Changelog-Generator/tree/0.0.1)
-#### 06/11/14
+#### 2014-11-06
 
 
-\* *This changelog was generated by [github_changelog_generator](https://github.com/skywinder/Github-Changelog-Generator)*
+\* *This changelog was generated by [github_changelog_generator](https://github.com/skywinder/Github-Changelog-Generator)*
\ No newline at end of file
diff --git a/lib/github_changelog_generator/parser.rb b/lib/github_changelog_generator/parser.rb
index 6aa4533..784ed2f 100644
--- a/lib/github_changelog_generator/parser.rb
+++ b/lib/github_changelog_generator/parser.rb
@@ -6,7 +6,7 @@ require_relative 'version'
 module GitHubChangelogGenerator
   class Parser
     def self.parse_options
-      options = {:tag1 => nil, :tag2 => nil, :format => '%d/%m/%y', :output => 'CHANGELOG.md', :labels => %w(bug enhancement), :pulls => true, :issues => true, :verbose => true, :add_issues_wo_labels => true, :merge_prefix => '*Merged pull-request:* ', :author => true, :pull_request_labels => nil, :filter_issues_by_milestone => true, :compare_link => true}
+      options = {:tag1 => nil, :tag2 => nil, :format => '%Y-%m-%d', :output => 'CHANGELOG.md', :labels => %w(bug enhancement), :pulls => true, :issues => true, :verbose => true, :add_issues_wo_labels => true, :merge_prefix => '*Merged pull-request:* ', :author => true, :pull_request_labels => nil, :filter_issues_by_milestone => true, :compare_link => true}
 
       parser = OptionParser.new { |opts|
         opts.banner = 'Usage: changelog_generator [options]'