diff --git a/.rubocop.yml b/.rubocop.yml
index 4640681379a..dc97a61b4a6 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -643,7 +643,7 @@ Metrics/ClassLength:
 # of test cases needed to validate a method.
 Metrics/CyclomaticComplexity:
   Enabled: true
-  Max: 14
+  Max: 13
 
 # Limit lines to 80 characters.
 Metrics/LineLength:
diff --git a/changelogs/unreleased/31362_decrease_cyclomatic_complexity_threshold_step4.yml b/changelogs/unreleased/31362_decrease_cyclomatic_complexity_threshold_step4.yml
new file mode 100644
index 00000000000..a404456198a
--- /dev/null
+++ b/changelogs/unreleased/31362_decrease_cyclomatic_complexity_threshold_step4.yml
@@ -0,0 +1,5 @@
+---
+title: Decrease Cyclomatic Complexity threshold to 13
+merge_request: 14152
+author: Maxim Rydkin
+type: other
diff --git a/lib/gitlab/conflict/parser.rb b/lib/gitlab/conflict/parser.rb
index 84f9ecd3d23..e3678c914db 100644
--- a/lib/gitlab/conflict/parser.rb
+++ b/lib/gitlab/conflict/parser.rb
@@ -12,12 +12,7 @@ module Gitlab
       MissingEndDelimiter = Class.new(ParserError)
 
       def parse(text, our_path:, their_path:, parent_file: nil)
-        raise UnmergeableFile if text.blank? # Typically a binary file
-        raise UnmergeableFile if text.length > 200.kilobytes
-
-        text.force_encoding('UTF-8')
-
-        raise UnsupportedEncoding unless text.valid_encoding?
+        validate_text!(text)
 
         line_obj_index = 0
         line_old = 1
@@ -32,15 +27,15 @@ module Gitlab
           full_line = line.delete("\n")
 
           if full_line == conflict_start
-            raise UnexpectedDelimiter unless type.nil?
+            validate_delimiter!(type.nil?)
 
             type = 'new'
           elsif full_line == conflict_middle
-            raise UnexpectedDelimiter unless type == 'new'
+            validate_delimiter!(type == 'new')
 
             type = 'old'
           elsif full_line == conflict_end
-            raise UnexpectedDelimiter unless type == 'old'
+            validate_delimiter!(type == 'old')
 
             type = nil
           elsif line[0] == '\\'
@@ -59,6 +54,21 @@ module Gitlab
 
         lines
       end
+
+      private
+
+      def validate_text!(text)
+        raise UnmergeableFile if text.blank? # Typically a binary file
+        raise UnmergeableFile if text.length > 200.kilobytes
+
+        text.force_encoding('UTF-8')
+
+        raise UnsupportedEncoding unless text.valid_encoding?
+      end
+
+      def validate_delimiter!(condition)
+        raise UnexpectedDelimiter unless condition
+      end
     end
   end
 end
diff --git a/lib/gitlab/mail_room.rb b/lib/gitlab/mail_room.rb
index 9f432673a6e..344784c866f 100644
--- a/lib/gitlab/mail_room.rb
+++ b/lib/gitlab/mail_room.rb
@@ -4,6 +4,15 @@ require_relative 'redis/queues' unless defined?(Gitlab::Redis::Queues)
 
 module Gitlab
   module MailRoom
+    DEFAULT_CONFIG = {
+      enabled: false,
+      port: 143,
+      ssl: false,
+      start_tls: false,
+      mailbox: 'inbox',
+      idle_timeout: 60
+    }.freeze
+
     class << self
       def enabled?
         config[:enabled] && config[:address]
@@ -22,16 +31,10 @@ module Gitlab
       def fetch_config
         return {} unless File.exist?(config_file)
 
-        rails_env = ENV['RAILS_ENV'] || ENV['RACK_ENV'] || 'development'
-        all_config = YAML.load_file(config_file)[rails_env].deep_symbolize_keys
-
-        config = all_config[:incoming_email] || {}
-        config[:enabled] = false if config[:enabled].nil?
-        config[:port] = 143 if config[:port].nil?
-        config[:ssl] = false if config[:ssl].nil?
-        config[:start_tls] = false if config[:start_tls].nil?
-        config[:mailbox] = 'inbox' if config[:mailbox].nil?
-        config[:idle_timeout] = 60 if config[:idle_timeout].nil?
+        config = YAML.load_file(config_file)[rails_env].deep_symbolize_keys[:incoming_email] || {}
+        config = DEFAULT_CONFIG.merge(config) do |_key, oldval, newval|
+          newval.nil? ? oldval : newval
+        end
 
         if config[:enabled] && config[:address]
           gitlab_redis_queues = Gitlab::Redis::Queues.new(rails_env)
@@ -45,6 +48,10 @@ module Gitlab
         config
       end
 
+      def rails_env
+        @rails_env ||= ENV['RAILS_ENV'] || ENV['RACK_ENV'] || 'development'
+      end
+
       def config_file
         ENV['MAIL_ROOM_GITLAB_CONFIG_FILE'] || File.expand_path('../../../config/gitlab.yml', __FILE__)
       end