diff --git a/debian/patches/0003-Ruby-3-support-615.patch b/debian/patches/0003-Ruby-3-support-615.patch
new file mode 100644
index 0000000..09db91d
--- /dev/null
+++ b/debian/patches/0003-Ruby-3-support-615.patch
@@ -0,0 +1,116 @@
+From: Koen Van der Auwera <atog@hey.com>
+Date: Mon, 17 May 2021 17:43:56 +0200
+Subject: Ruby 3 support (#615)
+
+* Remove warning: instance variable @json_output not initialized
+
+* Ruby 3 support.
+
+More specific for method_missing: Keyword arguments are separated from other argument
+https://www.ruby-lang.org/en/news/2020/12/25/ruby-3-0-0-released/
+
+* Need to remove the original one, duh.
+
+* Remove trailing whitespace
+
+* Use normalcase for variable numbers.
+
+* Prefer single-quoted strings when you don't need string interpolation or special symbols.
+
+* Do not use parentheses for method calls with no arguments
+
+* Refactored out use of `eval`.
+
+* Add empty line after guard clause
+
+* As suggested, use Gem::Version to compare Ruby version numbers.
+
+Origin: backport, https://github.com/NARKOZ/gitlab/commit/6fc4203d2e02
+Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=996236
+Reviewed-By: Lucas Kanashiro <kanashiro@debian.org>
+---
+ lib/gitlab.rb                              | 17 ++++++++++++-----
+ lib/gitlab/cli.rb                          |  2 +-
+ lib/gitlab/help.rb                         | 10 +++++-----
+ spec/gitlab/client/build_variables_spec.rb |  2 +-
+ 4 files changed, 19 insertions(+), 12 deletions(-)
+
+diff --git a/lib/gitlab.rb b/lib/gitlab.rb
+index 0a875bb..b87ba95 100644
+--- a/lib/gitlab.rb
++++ b/lib/gitlab.rb
+@@ -21,11 +21,18 @@ module Gitlab
+     Gitlab::Client.new(options)
+   end
+ 
+-  # Delegate to Gitlab::Client
+-  def self.method_missing(method, *args, &block)
+-    return super unless client.respond_to?(method)
+-
+-    client.send(method, *args, &block)
++  if Gem::Version.new(RUBY_VERSION).release >= Gem::Version.new('3.0.0')
++    def self.method_missing(method, *args, **keywargs, &block)
++      return super unless client.respond_to?(method)
++
++      client.send(method, *args, **keywargs, &block)
++    end
++  else
++    def self.method_missing(method, *args, &block)
++      return super unless client.respond_to?(method)
++
++      client.send(method, *args, &block)
++    end
+   end
+ 
+   # Delegate to Gitlab::Client
+diff --git a/lib/gitlab/cli.rb b/lib/gitlab/cli.rb
+index 5819bff..fb8be25 100644
+--- a/lib/gitlab/cli.rb
++++ b/lib/gitlab/cli.rb
+@@ -79,7 +79,7 @@ class Gitlab::CLI
+   # Helper method that checks whether we want to get the output as json
+   # @return [nil]
+   def self.render_output(cmd, args, data)
+-    if @json_output
++    if defined?(@json_output) && @json_output
+       output_json(cmd, args, data)
+     else
+       output_table(cmd, args, data)
+diff --git a/lib/gitlab/help.rb b/lib/gitlab/help.rb
+index f7ed37b..5469655 100644
+--- a/lib/gitlab/help.rb
++++ b/lib/gitlab/help.rb
+@@ -81,15 +81,15 @@ module Gitlab::Help
+     # Massage output from 'ri'.
+     def change_help_output!(cmd, output_str)
+       output_str = +output_str
+-      output_str.gsub!(/#{cmd}\((.*?)\)/m, "#{cmd} \1")
+-      output_str.gsub!(/,\s*/, ' ')
++      output_str.gsub!(/#{cmd}(\(.*?\))/m, "#{cmd}\\1")
++      output_str.gsub!(/,\s*/, ', ')
+ 
+       # Ensure @option descriptions are on a single line
+       output_str.gsub!(/\n\[/, " \[")
+       output_str.gsub!(/\s(@)/, "\n@")
+-      output_str.gsub!(/(\])\n(:)/, '\1 \2')
+-      output_str.gsub!(/(:.*)(\n)(.*\.)/, '\1 \3')
+-      output_str.gsub!(/\{(.+)\}/, '"{\1}"')
++      output_str.gsub!(/(\])\n(:)/, '\\1 \\2')
++      output_str.gsub!(/(:.*)(\n)(.*\.)/, '\\1 \\3')
++      output_str.gsub!(/\{(.+)\}/, '"{\\1}"')
+     end
+   end
+ end
+diff --git a/spec/gitlab/client/build_variables_spec.rb b/spec/gitlab/client/build_variables_spec.rb
+index 77672f5..d09f8e0 100644
+--- a/spec/gitlab/client/build_variables_spec.rb
++++ b/spec/gitlab/client/build_variables_spec.rb
+@@ -38,7 +38,7 @@ describe Gitlab::Client do
+ 
+   describe '.create_variable' do
+     before do
+-      stub_post('/projects/3/variables', 'variable')
++      stub_post('/projects/3/variables', 'variable', { masked: true })
+       @variable = Gitlab.create_variable(3, 'NEW_VARIABLE', 'new value')
+     end
+ 
diff --git a/debian/patches/series b/debian/patches/series
index a0d7a11..97147c0 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -1,2 +1,3 @@
 use-installed-libraries.patch
 relax-dependency-terminal-table.patch
+0003-Ruby-3-support-615.patch