diff --git a/.travis.yml b/.travis.yml
index e42ee87..8a9a08c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@ sudo: false
 
 matrix:
   include:
-    - rvm: 2.5.3
+    - rvm: 2.6.6
       env:
         - MONGOID_VERSION=7
     - rvm: 2.3.1
@@ -15,12 +15,6 @@ matrix:
     - rvm: 2.3.1
       env:
         - MONGOID_VERSION=5
-    - rvm: 2.2
-      env:
-        - MONGOID_VERSION=4
-    - rvm: 2.5.3
-      env:
-        - MONGOID_VERSION=3
     - rvm: jruby-head
     - rvm: rbx-2
     - rvm: ruby-head
@@ -30,10 +24,3 @@ matrix:
     - rvm: ruby-head
 
 services: mongodb
-
-addons:
-  apt:
-    sources:
-      - mongodb-3.2-precise
-    packages:
-      - mongodb-org-server
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4dedf6e..351ebdc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,12 @@
-### 2.3.2 (Next)
+### 3.0.1 (Next)
 
 * Your contribution here.
 
+### 3.0.0 (2019/02/26)
+
+* [#81](https://github.com/collectiveidea/delayed_job_mongoid/pull/81): Drop support for Mongoid 3.0 and 4.0 - [johnnyshields](https://github.com/johnnyshields).
+* [#81](https://github.com/collectiveidea/delayed_job_mongoid/pull/81): Perform disconnect on after_fork on all Mongoid versions - [johnnyshields](https://github.com/johnnyshields).
+
 ### 2.3.1 (2019/02/26)
 
 * [#77](https://github.com/collectiveidea/delayed_job_mongoid/pull/77): Support Mongoid 7.0 - [Startouf](https://github.com/Startouf).
diff --git a/Gemfile b/Gemfile
index 2d4b512..a981f57 100644
--- a/Gemfile
+++ b/Gemfile
@@ -20,10 +20,6 @@ when /^6/
   gem 'mongoid', '~> 6.0'
 when /^5/
   gem 'mongoid', '~> 5.0'
-when /^4/
-  gem 'mongoid', '~> 4.0'
-when /^3/
-  gem 'mongoid', '~> 3.1'
 else
   gem 'mongoid', version
 end
diff --git a/README.md b/README.md
index 24a7073..b85ed6a 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,9 @@
 
 ## Requirements
 
-Mongoid 3, 4, 5, 6 or 7.
+Mongoid 5 or later.
+
+(For Mongoid 3 and 4, use 2.x version of this gem)
 
 ## Installation
 
@@ -28,5 +30,4 @@ To generate `script/delayed_job`:
 
     rails generate delayed_job
 
-That's it. Use [delayed_job](http://github.com/collectiveidea/delayed_job) as
-normal.
+That's it. Use [delayed_job](http://github.com/collectiveidea/delayed_job) as normal.
diff --git a/delayed_job_mongoid.gemspec b/delayed_job_mongoid.gemspec
index 89c2429..2affebf 100644
--- a/delayed_job_mongoid.gemspec
+++ b/delayed_job_mongoid.gemspec
@@ -1,14 +1,13 @@
 Gem::Specification.new do |spec|
   spec.add_dependency 'delayed_job', ['>= 3.0', '< 5']
-  spec.add_dependency 'mongoid', ['>= 3.0', '< 8']
-  spec.add_dependency 'mongoid-compatibility', '>= 0.4.0'
-  spec.authors         = ['Chris Gaffney', 'Brandon Keepers', 'Erik Michaels-Ober']
-  spec.email           = ['chris@collectiveidea.com', 'brandon@opensoul.com', 'sferik@gmail.com']
-  spec.files           = %w[CHANGELOG.md CONTRIBUTING.md LICENSE.md README.md delayed_job_mongoid.gemspec] + Dir['lib/**/*.rb']
-  spec.homepage        = 'http://github.com/collectiveidea/delayed_job_mongoid'
-  spec.licenses        = ['MIT']
-  spec.name            = 'delayed_job_mongoid'
-  spec.require_paths   = ['lib']
-  spec.summary         = 'Mongoid backend for delayed_job'
-  spec.version         = '2.3.2'
+  spec.add_dependency 'mongoid', '>= 5.0'
+  spec.authors        = ['Chris Gaffney', 'Brandon Keepers', 'Erik Michaels-Ober']
+  spec.email          = ['chris@collectiveidea.com', 'brandon@opensoul.com', 'sferik@gmail.com']
+  spec.files          = %w[CHANGELOG.md CONTRIBUTING.md LICENSE.md README.md delayed_job_mongoid.gemspec] + Dir['lib/**/*.rb']
+  spec.homepage       = 'http://github.com/collectiveidea/delayed_job_mongoid'
+  spec.licenses       = ['MIT']
+  spec.name           = 'delayed_job_mongoid'
+  spec.require_paths  = ['lib']
+  spec.summary        = 'Mongoid backend for delayed_job'
+  spec.version        = '3.0.0'
 end
diff --git a/lib/delayed/backend/mongoid.rb b/lib/delayed/backend/mongoid.rb
index d8a7f13..8ac8d43 100644
--- a/lib/delayed/backend/mongoid.rb
+++ b/lib/delayed/backend/mongoid.rb
@@ -1,6 +1,5 @@
 require 'delayed_job'
 require 'mongoid'
-require 'mongoid/compatibility'
 
 module Delayed
   module Backend
@@ -33,20 +32,11 @@ def self.db_time_now
         # Atomically picks and locks one job from the collection.
         def self.reserve(worker, max_run_time = Worker.max_run_time)
           right_now = db_time_now
-
-          criteria = reservation_criteria worker, right_now, max_run_time
-
-          if ::Mongoid::Compatibility::Version.mongoid2? || ::Mongoid::Compatibility::Version.mongoid3? || ::Mongoid::Compatibility::Version.mongoid4?
-            criteria.find_and_modify(
-              { '$set' => { locked_at: right_now, locked_by: worker.name } },
-              new: true
-            )
-          else
-            criteria.find_one_and_update(
-              { '$set' => { locked_at: right_now, locked_by: worker.name } },
-              return_document: :after
-            )
-          end
+          criteria = reservation_criteria(worker, right_now, max_run_time)
+          criteria.find_one_and_update(
+            { '$set' => { locked_at: right_now, locked_by: worker.name } },
+            return_document: :after
+          )
         end
 
         # Mongo criteria matching all the jobs the worker can reserver
@@ -84,10 +74,7 @@ def reload(*args)
 
         # Hook method that is called after a new worker is forked
         def self.after_fork
-          if ::Mongoid::Compatibility::Version.mongoid4?
-            # to avoid `failed with error "unauthorized"` errors in Mongoid 4.0.alpha2
-            ::Mongoid.default_session.disconnect
-          end
+          ::Mongoid.disconnect_clients
         end
       end
     end
diff --git a/lib/delayed/plugins.rb b/lib/delayed/plugins.rb
deleted file mode 100644
index b972ead..0000000
--- a/lib/delayed/plugins.rb
+++ /dev/null
@@ -1,19 +0,0 @@
-#
-# clear Mongoid::IdentityMap before each job
-#
-
-if ::Mongoid::Compatibility::Version.mongoid3?
-  module Delayed
-    module Plugins
-      class ClearIdentityMap < Plugin
-        callbacks do |lifecycle|
-          lifecycle.before(:invoke_job) do
-            Mongoid::IdentityMap.clear
-          end
-        end
-      end
-    end
-  end
-
-  Delayed::Worker.plugins << Delayed::Plugins::ClearIdentityMap
-end
diff --git a/lib/delayed_job_mongoid.rb b/lib/delayed_job_mongoid.rb
index 040c1d0..beeea52 100644
--- a/lib/delayed_job_mongoid.rb
+++ b/lib/delayed_job_mongoid.rb
@@ -1,7 +1,6 @@
 require 'delayed/backend/mongoid'
 require 'delayed/serialization/mongoid'
 require 'delayed_job'
-require 'delayed/plugins'
 require 'delayed/yaml/yaml_ext'
 
 Delayed::Worker.backend = :mongoid
diff --git a/spec/helper.rb b/spec/helper.rb
index be47aef..57acc0c 100644
--- a/spec/helper.rb
+++ b/spec/helper.rb
@@ -11,15 +11,15 @@
 require 'rspec'
 require 'delayed_job_mongoid'
 require 'delayed/backend/shared_spec'
-require 'mongoid/compatibility'
 
 RSpec.configure do |config|
   config.expect_with :rspec do |c|
     c.syntax = :expect
   end
+
   config.before :all do
     Mongoid.logger.level = Logger::INFO
-    Mongo::Logger.logger.level = Logger::INFO if Mongoid::Compatibility::Version.mongoid5? || Mongoid::Compatibility::Version.mongoid6?
+    Mongo::Logger.logger.level = Logger::INFO
   end
 end
 
diff --git a/spec/plugins_spec.rb b/spec/plugins_spec.rb
deleted file mode 100644
index eceabe0..0000000
--- a/spec/plugins_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require 'helper'
-
-if ::Mongoid::Compatibility::Version.mongoid3?
-  describe Delayed::Backend::Mongoid::Job do
-    let(:worker) { Delayed::Worker.new }
-    before do
-      Delayed::Worker.max_priority = nil
-      Delayed::Worker.min_priority = nil
-      Delayed::Worker.default_priority = 99
-      Delayed::Worker.delay_jobs = true
-      SimpleJob.runs = 0
-      described_class.delete_all
-    end
-    after do
-      Delayed::Worker.reset
-    end
-    it 'clears mongoid identity map' do
-      expect(Mongoid::IdentityMap).to receive(:clear).once
-      described_class.enqueue SimpleJob.new, priority: 5
-      worker.work_off
-    end
-  end
-end