diff --git a/REFACTOR.md b/REFACTOR.md
new file mode 100644
index 00000000..8eb7a41c
--- /dev/null
+++ b/REFACTOR.md
@@ -0,0 +1 @@
+20200703113000: `require "celluloid/current"` is removed. use `require "celluloid"`
diff --git a/examples/configurations.rb b/examples/configurations.rb
index 121bf25f..76bc1416 100644
--- a/examples/configurations.rb
+++ b/examples/configurations.rb
@@ -1,4 +1,4 @@
-require "celluloid/current"
+require "celluloid"
 
 puts "Use Supervision::Configuration objects!"
 
diff --git a/examples/timers.rb b/examples/timers.rb
index e5c523ab..ec5d01fd 100755
--- a/examples/timers.rb
+++ b/examples/timers.rb
@@ -1,7 +1,7 @@
 #!/usr/bin/env ruby
 
 $LOAD_PATH.push File.expand_path("../lib", __dir__)
-require "celluloid/current"
+require "celluloid"
 
 class TimerExample
   include Celluloid
diff --git a/lib/celluloid/backported.rb b/lib/celluloid/backported.rb
deleted file mode 100644
index fb4526aa..00000000
--- a/lib/celluloid/backported.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-raise NotImplementedError, <<-MSG.strip.gsub(/\s+/, " ")
-  Celluloid 0.18 no-longer supports the "backported" API.
-  Please switch to using: `require 'celluloid'`
-  For more information, see:
-  https://github.com/celluloid/celluloid/wiki/0.18-API-changes
-MSG
diff --git a/lib/celluloid/current.rb b/lib/celluloid/current.rb
deleted file mode 100644
index 2a02693c..00000000
--- a/lib/celluloid/current.rb
+++ /dev/null
@@ -1,4 +0,0 @@
-# Legacy support for the prescribed 0.17 API
-# TODO: remove this in a future release
-
-require "celluloid"
diff --git a/lib/celluloid/managed.rb b/lib/celluloid/managed.rb
deleted file mode 100644
index 32956ba0..00000000
--- a/lib/celluloid/managed.rb
+++ /dev/null
@@ -1,6 +0,0 @@
-raise NotImplementedError, <<-MSG.strip.gsub(/\s+/, " ")
-  Celluloid 0.18 no-longer supports the "managed" API.
-  Please switch to using: `require 'celluloid'`
-  For more information, see:
-  https://github.com/celluloid/celluloid/wiki/0.18-API-changes
-MSG
diff --git a/lib/celluloid/supervision/container/tree.rb b/lib/celluloid/supervision/container/tree.rb
deleted file mode 100644
index e69de29b..00000000
diff --git a/lib/celluloid/supervision/deprecate.rb b/lib/celluloid/supervision/deprecate.rb
deleted file mode 100644
index 1990eb62..00000000
--- a/lib/celluloid/supervision/deprecate.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-# TODO: Remove at 0.19.0
-module Celluloid
-  SupervisionGroup = Supervision::Container
-  Supervision::Group = Supervision::Container
-  Supervision::Member = Supervision::Container::Instance
-end
-
-require "celluloid/supervision/deprecate/supervise"
-require "celluloid/supervision/deprecate/validation"
diff --git a/lib/celluloid/supervision/deprecate/supervise.rb b/lib/celluloid/supervision/deprecate/supervise.rb
deleted file mode 100644
index 29932491..00000000
--- a/lib/celluloid/supervision/deprecate/supervise.rb
+++ /dev/null
@@ -1,105 +0,0 @@
-# TODO: Remove at 0.19.0
-module Celluloid
-  class << self
-    undef supervise rescue nil
-    def supervise(*args, &block)
-      supervisor = Supervision.router(*args)
-      supervisor.supervise(*args, &block)
-    end
-    undef supervise_as rescue nil
-    def supervise_as(name, *args, &block)
-      supervisor = Supervision.router(*args)
-      supervisor.supervise_as(name, *args, &block)
-    end
-  end
-  module ClassMethods
-    undef supervise rescue nil
-    def supervise(*args, &block)
-      args.unshift(self)
-      Celluloid.supervise(*args, &block)
-    end
-    undef supervise_as rescue nil
-    def supervise_as(name, *args, &block)
-      args.unshift(self)
-      Celluloid.supervise_as(name, *args, &block)
-    end
-  end
-
-  # Supervisors are actors that watch over other actors and restart them if
-  # they crash
-  class Supervisor
-    class << self
-      # Define the root of the supervision tree
-      attr_accessor :root
-
-      undef supervise rescue nil
-      def supervise(klass, *args, &block)
-        args.unshift(klass)
-        Celluloid.supervise(*args, &block)
-      end
-
-      undef supervise_as rescue nil
-      def supervise_as(name, klass, *args, &block)
-        args.unshift(klass)
-        Celluloid.supervise_as(name, *args, &block)
-      end
-    end
-  end
-
-  module Supervision
-    class << self
-      undef router rescue nil
-      def router(*_args)
-        # TODO: Actually route, based on :branch, if present; or else:
-        Celluloid.services
-      end
-    end
-    class Container
-      class << self
-        undef run! rescue nil
-        def run!(*args)
-          container = new(*args) do |g|
-            blocks.each do |block|
-              block.call(g)
-            end
-          end
-          container
-        end
-
-        undef run rescue nil
-        def run(*args)
-          loop do
-            supervisor = run!(*args)
-            # Take five, toplevel supervisor
-            sleep 5 while supervisor.alive? # Why 5?
-            Internals::Logger.error "!!! Celluloid::Supervision::Container #{self} crashed. Restarting..."
-          end
-        end
-
-        undef supervise rescue nil
-        def supervise(*args, &block)
-          blocks << lambda do |container|
-            container.supervise(*args, &block)
-          end
-        end
-
-        undef supervise_as rescue nil
-        def supervise_as(name, *args, &block)
-          blocks << lambda do |container|
-            container.supervise_as(name, *args, &block)
-          end
-        end
-      end
-
-      undef supervise rescue nil
-      def supervise(*args, &block)
-        add(Configuration.options(args, block: block))
-      end
-
-      undef supervise_as rescue nil
-      def supervise_as(name, *args, &block)
-        add(Configuration.options(args, block: block, as: name))
-      end
-    end
-  end
-end
diff --git a/lib/celluloid/supervision/deprecate/validation.rb b/lib/celluloid/supervision/deprecate/validation.rb
deleted file mode 100644
index 8c5df685..00000000
--- a/lib/celluloid/supervision/deprecate/validation.rb
+++ /dev/null
@@ -1,54 +0,0 @@
-module Celluloid
-  module Supervision
-    class Configuration
-      class << self
-        # argument scenarios:
-        #   * only class ( becomes :type )
-        #   * class ( becomes :type ), hash*
-        #   * hash ( *with :type, and perhaps :as, :size, :args, :block, :registry )
-        #          ( any keys expected are pulled out: may want to check on arity? )
-        #          ( the pulling out of keys is where danger mentioned above comes )
-        undef parse rescue nil
-        def parse(args)
-          return args if args.is_a? Configuration::Instance
-          options = { args: [] }
-          return { type: args } if args.is_a? Class
-          if args.is_a? Hash
-            return args
-          elsif args.is_a? Array
-            if args.length == 1
-              return args[0] if args.first.is_a? Configuration::Instance
-              return { type: args.first } if args.first.is_a? Class
-              if args.first.is_a?(Hash) && args = args.pop
-                return args
-              end
-              options[:args] = args if args.any?
-            elsif args.length > 1
-              # TODO: don't use each
-              options.merge! args.pop if args.last.is_a? Hash
-              options[:type] = args.shift if args.first.is_a? Class
-              options[:args] += args if args.any?
-            end
-          end
-          options
-        end
-
-        # This is dangerous. It is temporary, until `Supervision::Configuration` is entrenched.
-        # Since :type, :as, etc are used by the supervision group/member to initialize,
-        # those will not appear in the resulting actor's initialize call.
-        undef options rescue nil
-        def options(args, options = {})
-          return args.merge!(options) if args.is_a? Configuration::Instance
-          # Not a Supervision:Configuration?
-          # Try to guess its structure and build one:
-          options = parse(args).merge(options)
-          options[:configuration] = Container::Behavior.configure(options)
-          options[:args].compact! if options[:args].is_a? Array
-          options.reject! { |_k, v| v.nil? }
-          Configuration.valid? options, true
-          options
-        end
-      end
-    end
-  end
-end