diff --git a/lib/github_changelog_generator/octo_fetcher.rb b/lib/github_changelog_generator/octo_fetcher.rb
index d173631..52e4c12 100644
--- a/lib/github_changelog_generator/octo_fetcher.rb
+++ b/lib/github_changelog_generator/octo_fetcher.rb
@@ -200,6 +200,7 @@ Make sure, that you push tags to remote repo via 'git push --tags'".yellow
     # @return [Time] time of specified tag
     def fetch_date_of_tag(tag)
       commit_data = check_github_response { @client.commit(user_project, tag['commit']['sha']) }
+      commit_data = commit_data.to_hash.stringify_keys_deep!
 
       commit_data['commit']['committer']['date']
     end
diff --git a/spec/unit/octo_fetcher_spec.rb b/spec/unit/octo_fetcher_spec.rb
index 841d14d..0460e95 100644
--- a/spec/unit/octo_fetcher_spec.rb
+++ b/spec/unit/octo_fetcher_spec.rb
@@ -172,10 +172,10 @@ describe GitHubChangelogGenerator::OctoFetcher do
         issues = [{"url"=>"https://api.github.com/repos/skywinder/changelog_test/issues/14", "repository_url"=>"https://api.github.com/repos/skywinder/changelog_test", "labels_url"=>"https://api.github.com/repos/skywinder/changelog_test/issues/14/labels{/name}", "comments_url"=>"https://api.github.com/repos/skywinder/changelog_test/issues/14/comments", "events_url"=>"https://api.github.com/repos/skywinder/changelog_test/issues/14/events", "html_url"=>"https://github.com/skywinder/changelog_test/issues/14", "id"=>95419412, "number"=>14, "title"=>"Issue closed from commit from PR", "user"=>{"login"=>"skywinder", "id"=>3356474, "avatar_url"=>"https://avatars.githubusercontent.com/u/3356474?v=3", "gravatar_id"=>"", "url"=>"https://api.github.com/users/skywinder", "html_url"=>"https://github.com/skywinder", "followers_url"=>"https://api.github.com/users/skywinder/followers", "following_url"=>"https://api.github.com/users/skywinder/following{/other_user}", "gists_url"=>"https://api.github.com/users/skywinder/gists{/gist_id}", "starred_url"=>"https://api.github.com/users/skywinder/starred{/owner}{/repo}", "subscriptions_url"=>"https://api.github.com/users/skywinder/subscriptions", "organizations_url"=>"https://api.github.com/users/skywinder/orgs", "repos_url"=>"https://api.github.com/users/skywinder/repos", "events_url"=>"https://api.github.com/users/skywinder/events{/privacy}", "received_events_url"=>"https://api.github.com/users/skywinder/received_events", "type"=>"User", "site_admin"=>false}, "labels"=>[], "state"=>"closed", "locked"=>false, "assignee"=>nil, "milestone"=>nil, "comments"=>0, "created_at"=>"2015-07-16T12:06:08Z", "updated_at"=>"2015-07-16T12:21:42Z", "closed_at"=>"2015-07-16T12:21:42Z", "body"=>""}]
 
         # Check that they are blank to begin with
-        expect(issues.first[:events]).to be_nil
+        expect(issues.first['events']).to be_nil
 
         fetcher.fetch_events_async(issues)
-        issue_events = issues.first[:events]
+        issue_events = issues.first['events']
 
         expected_events = [{"id"=>357462189, "url"=>"https://api.github.com/repos/skywinder/changelog_test/issues/events/357462189", "actor"=>{"login"=>"skywinder", "id"=>3356474, "avatar_url"=>"https://avatars.githubusercontent.com/u/3356474?v=3", "gravatar_id"=>"", "url"=>"https://api.github.com/users/skywinder", "html_url"=>"https://github.com/skywinder", "followers_url"=>"https://api.github.com/users/skywinder/followers", "following_url"=>"https://api.github.com/users/skywinder/following{/other_user}", "gists_url"=>"https://api.github.com/users/skywinder/gists{/gist_id}", "starred_url"=>"https://api.github.com/users/skywinder/starred{/owner}{/repo}", "subscriptions_url"=>"https://api.github.com/users/skywinder/subscriptions", "organizations_url"=>"https://api.github.com/users/skywinder/orgs", "repos_url"=>"https://api.github.com/users/skywinder/repos", "events_url"=>"https://api.github.com/users/skywinder/events{/privacy}", "received_events_url"=>"https://api.github.com/users/skywinder/received_events", "type"=>"User", "site_admin"=>false}, "event"=>"referenced", "commit_id"=>"decfe840d1a1b86e0c28700de5362d3365a29555", "commit_url"=>"https://api.github.com/repos/skywinder/changelog_test/commits/decfe840d1a1b86e0c28700de5362d3365a29555", "created_at"=>"2015-07-16T12:21:16Z"}, {"id"=>357462542, "url"=>"https://api.github.com/repos/skywinder/changelog_test/issues/events/357462542", "actor"=>{"login"=>"skywinder", "id"=>3356474, "avatar_url"=>"https://avatars.githubusercontent.com/u/3356474?v=3", "gravatar_id"=>"", "url"=>"https://api.github.com/users/skywinder", "html_url"=>"https://github.com/skywinder", "followers_url"=>"https://api.github.com/users/skywinder/followers", "following_url"=>"https://api.github.com/users/skywinder/following{/other_user}", "gists_url"=>"https://api.github.com/users/skywinder/gists{/gist_id}", "starred_url"=>"https://api.github.com/users/skywinder/starred{/owner}{/repo}", "subscriptions_url"=>"https://api.github.com/users/skywinder/subscriptions", "organizations_url"=>"https://api.github.com/users/skywinder/orgs", "repos_url"=>"https://api.github.com/users/skywinder/repos", "events_url"=>"https://api.github.com/users/skywinder/events{/privacy}", "received_events_url"=>"https://api.github.com/users/skywinder/received_events", "type"=>"User", "site_admin"=>false}, "event"=>"closed", "commit_id"=>"decfe840d1a1b86e0c28700de5362d3365a29555", "commit_url"=>"https://api.github.com/repos/skywinder/changelog_test/commits/decfe840d1a1b86e0c28700de5362d3365a29555", "created_at"=>"2015-07-16T12:21:42Z"}]