diff --git a/.ruby-version b/.ruby-version
new file mode 100644
index 0000000..49cdd66
--- /dev/null
+++ b/.ruby-version
@@ -0,0 +1 @@
+2.7.6
diff --git a/lib/sidekiq-rate-limiter/server.rb b/lib/sidekiq-rate-limiter/server.rb
index e08d478..85eb2ae 100644
--- a/lib/sidekiq-rate-limiter/server.rb
+++ b/lib/sidekiq-rate-limiter/server.rb
@@ -2,5 +2,12 @@
 require 'sidekiq-rate-limiter/fetch'
 
 Sidekiq.configure_server do |config|
-  Sidekiq.options[:fetch] = Sidekiq::RateLimiter::Fetch
+  # Backwards compatibility for Sidekiq < 6.1.0 (see https://github.com/mperham/sidekiq/pull/4602 for details)
+  if (Sidekiq::BasicFetch.respond_to?(:bulk_requeue))
+    Sidekiq.options[:fetch] = Sidekiq::RateLimiter::Fetch
+  elsif (Sidekiq::VERSION < '6.5.0') # Sidekiq config was redesigned in https://github.com/mperham/sidekiq/pull/5340
+    Sidekiq.options[:fetch] = Sidekiq::RateLimiter::Fetch.new(Sidekiq.options)
+  else
+    Sidekiq[:fetch] = Sidekiq::RateLimiter::Fetch.new(Sidekiq)
+  end
 end
diff --git a/spec/sidekiq-rate-limiter/fetch_spec.rb b/spec/sidekiq-rate-limiter/fetch_spec.rb
index 5a780fe..5b4d98e 100644
--- a/spec/sidekiq-rate-limiter/fetch_spec.rb
+++ b/spec/sidekiq-rate-limiter/fetch_spec.rb
@@ -27,7 +27,11 @@ def perform(arg1, arg2); end
     end
   end
 
-  let(:options)       { { queues: [queue, another_queue, another_queue] } }
+  let(:options)       {
+    s = Sidekiq
+    s[:queues] = [queue, another_queue, another_queue]
+    s
+  }
   let(:queue)         { 'basic' }
   let(:another_queue) { 'some_other_queue' }
   let(:args)          { ['I am some args'] }
@@ -47,7 +51,7 @@ def perform(arg1, arg2); end
         Sidekiq::Fetcher::TIMEOUT
       end
 
-    fetch = described_class.new options.merge(:strict => true)
+    fetch = described_class.new options.merge!(:strict => true)
     expect(fetch.queues_cmd).to eql(["queue:#{queue}", "queue:#{another_queue}", timeout])
   end
 
diff --git a/spec/sidekiq-rate-limiter/server_spec.rb b/spec/sidekiq-rate-limiter/server_spec.rb
index ae086de..3cf4f41 100644
--- a/spec/sidekiq-rate-limiter/server_spec.rb
+++ b/spec/sidekiq-rate-limiter/server_spec.rb
@@ -8,13 +8,13 @@
 
   it 'should set Sidekiq.options[:fetch] as desired' do
     Sidekiq.configure_server do |config|
-      expect(Sidekiq.options[:fetch]).to eql(Sidekiq::RateLimiter::Fetch)
+      expect(Sidekiq.options[:fetch]).to be_a(Sidekiq::RateLimiter::Fetch)
     end
   end
 
   it 'should inherit from Sidekiq::BasicFetch' do
     Sidekiq.configure_server do |config|
-      expect(Sidekiq.options[:fetch]).to be < Sidekiq::BasicFetch
+      expect(Sidekiq.options[:fetch].class.ancestors[1]).to be(Sidekiq::BasicFetch)
     end
   end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index f7d062a..6c29688 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,5 +1,6 @@
 require 'sidekiq'
 require 'sidekiq/testing'
+require 'pry-byebug'
 
 ## Confirming presence of redis server executable
 abort "## `redis-server` not in path" if %x(which redis-server).empty?