diff --git a/lib/github_changelog_generator/generator/generator_fetcher.rb b/lib/github_changelog_generator/generator/generator_fetcher.rb
index 22c03aa..8f93f62 100644
--- a/lib/github_changelog_generator/generator/generator_fetcher.rb
+++ b/lib/github_changelog_generator/generator/generator_fetcher.rb
@@ -1,6 +1,8 @@
 # frozen_string_literal: true
 module GitHubChangelogGenerator
   class Generator
+    MAX_THREAD_NUMBER = 4
+
     # Fetch event for issues and pull requests
     # @return [Array] array of fetched issues
     def fetch_events_for_issues_and_pr
@@ -35,8 +37,7 @@ module GitHubChangelogGenerator
     def detect_actual_closed_dates(issues)
       print "Fetching closed dates for issues...\r" if @options[:verbose]
 
-      max_thread_number = 50
-      issues.each_slice(max_thread_number) do |issues_slice|
+      issues.each_slice(MAX_THREAD_NUMBER) do |issues_slice|
         threads = []
         issues_slice.each do |issue|
           threads << Thread.new { find_closed_date_by_commit(issue) }
diff --git a/lib/github_changelog_generator/octo_fetcher.rb b/lib/github_changelog_generator/octo_fetcher.rb
index 8934d3a..e26b067 100644
--- a/lib/github_changelog_generator/octo_fetcher.rb
+++ b/lib/github_changelog_generator/octo_fetcher.rb
@@ -7,7 +7,7 @@ module GitHubChangelogGenerator
 
   class OctoFetcher
     PER_PAGE_NUMBER   = 100
-    MAX_THREAD_NUMBER = 50
+    MAX_THREAD_NUMBER = 4
     CHANGELOG_GITHUB_TOKEN = "CHANGELOG_GITHUB_TOKEN"
     GH_RATE_LIMIT_EXCEEDED_MSG = "Warning: Can't finish operation: GitHub API rate limit exceeded, change log may be " \
     "missing some issues. You can limit the number of issues fetched using the `--max-issues NUM` argument."