diff --git a/.rubocop.yml b/.rubocop.yml
index 51d21cc87..0ca61a12b 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -264,8 +264,6 @@ Lint/ShadowingOuterLocalVariable:
   Enabled: false
 Style/InfiniteLoop:
   Enabled: false
-Lint/AmbiguousRegexpLiteral:
-  Enabled: false
 Lint/Eval:
   Enabled: false
 Style/ModuleFunction:
diff --git a/app/controllers/tickets_controller.rb b/app/controllers/tickets_controller.rb
index 491c37db9..a67d48f34 100644
--- a/app/controllers/tickets_controller.rb
+++ b/app/controllers/tickets_controller.rb
@@ -38,7 +38,7 @@ class TicketsController < ApplicationController
 
     # create tags if given
     if params[:tags] && !params[:tags].empty?
-      tags = params[:tags].split /,/
+      tags = params[:tags].split(/,/)
       tags.each {|tag|
         Tag.tag_add(
           object: 'Ticket',
diff --git a/app/models/ticket/subject.rb b/app/models/ticket/subject.rb
index 7a7f61163..15d19dcc2 100644
--- a/app/models/ticket/subject.rb
+++ b/app/models/ticket/subject.rb
@@ -56,17 +56,17 @@ returns
     ticket_subject_size = Setting.get('ticket_subject_size')
 
     # remove all possible ticket hook formats with []
-    subject = subject.gsub /\[#{ticket_hook}: #{self.number}\](\s+?|)/, ''
-    subject = subject.gsub /\[#{ticket_hook}:#{self.number}\](\s+?|)/, ''
-    subject = subject.gsub /\[#{ticket_hook}#{ticket_hook_divider}#{self.number}\](\s+?|)/, ''
+    subject = subject.gsub(/\[#{ticket_hook}: #{self.number}\](\s+?|)/, '')
+    subject = subject.gsub(/\[#{ticket_hook}:#{self.number}\](\s+?|)/, '')
+    subject = subject.gsub(/\[#{ticket_hook}#{ticket_hook_divider}#{self.number}\](\s+?|)/, '')
 
     # remove all possible ticket hook formats without []
-    subject = subject.gsub /#{ticket_hook}: #{self.number}(\s+?|)/, ''
-    subject = subject.gsub /#{ticket_hook}:#{self.number}(\s+?|)/, ''
-    subject = subject.gsub /#{ticket_hook}#{ticket_hook_divider}#{self.number}(\s+?|)/, ''
+    subject = subject.gsub(/#{ticket_hook}: #{self.number}(\s+?|)/, '')
+    subject = subject.gsub(/#{ticket_hook}:#{self.number}(\s+?|)/, '')
+    subject = subject.gsub(/#{ticket_hook}#{ticket_hook_divider}#{self.number}(\s+?|)/, '')
 
     # remove leading "..:\s" and "..[\d+]:\s" e. g. "Re: " or "Re[5]: "
-    subject = subject.gsub /^(..(\[\d+\])?:\s)+/, ''
+    subject = subject.gsub(/^(..(\[\d+\])?:\s)+/, '')
 
     # resize subject based on config
     if subject.length > ticket_subject_size.to_i