diff --git a/lib/irb/completion.rb b/lib/irb/completion.rb
index 0fdb85ab4..26215f6fe 100644
--- a/lib/irb/completion.rb
+++ b/lib/irb/completion.rb
@@ -9,15 +9,11 @@
 
 module IRB
   class BaseCompletor # :nodoc:
-    def initialize(target, preposing = nil, postposing = nil)
+    def completion_candidates(preposing, target, postposing, bind:)
       raise NotImplementedError
     end
 
-    def completion_candidates
-      raise NotImplementedError
-    end
-
-    def doc_namespace(matched)
+    def doc_namespace(preposing, matched, postposing, bind:)
       raise NotImplementedError
     end
 
@@ -36,7 +32,7 @@ def doc_namespace(matched)
         []
       end.freeze
 
-    def self.retrieve_gem_and_system_load_path
+    def retrieve_gem_and_system_load_path
       candidates = (GEM_PATHS | $LOAD_PATH)
       candidates.map do |p|
         if p.respond_to?(:to_path)
@@ -47,8 +43,8 @@ def self.retrieve_gem_and_system_load_path
       end.compact.sort
     end
 
-    def self.retrieve_files_to_require_from_load_path
-      @@files_from_load_path ||=
+    def retrieve_files_to_require_from_load_path
+      @files_from_load_path ||=
         (
           shortest = []
           rest = retrieve_gem_and_system_load_path.each_with_object([]) { |path, result|
@@ -66,8 +62,8 @@ def self.retrieve_files_to_require_from_load_path
         )
     end
 
-    def self.retrieve_files_to_require_relative_from_current_dir
-      @@files_from_current_dir ||= Dir.glob("**/*.{rb,#{RbConfig::CONFIG['DLEXT']}}", base: '.').map { |path|
+    def retrieve_files_to_require_relative_from_current_dir
+      @files_from_current_dir ||= Dir.glob("**/*.{rb,#{RbConfig::CONFIG['DLEXT']}}", base: '.').map { |path|
         path.sub(/\.(rb|#{RbConfig::CONFIG['DLEXT']})\z/, '')
       }
     end
@@ -140,13 +136,13 @@ def complete_require_path(target, preposing, postposing)
       if tok && tok.event == :on_ident && tok.state == Ripper::EXPR_CMDARG
         case tok.tok
         when 'require'
-          result = BaseCompletor.retrieve_files_to_require_from_load_path.select { |path|
+          result = retrieve_files_to_require_from_load_path.select { |path|
             path.start_with?(actual_target)
           }.map { |path|
             quote + path
           }
         when 'require_relative'
-          result = BaseCompletor.retrieve_files_to_require_relative_from_current_dir.select { |path|
+          result = retrieve_files_to_require_relative_from_current_dir.select { |path|
             path.start_with?(actual_target)
           }.map { |path|
             quote + path
@@ -156,23 +152,16 @@ def complete_require_path(target, preposing, postposing)
       result
     end
 
-    def initialize(target, preposing, postposing, bind:)
-      @target = target
-      @preposing = preposing
-      @postposing = postposing
-      @binding = bind
-    end
-
-    def completion_candidates
-      if @preposing && @postposing
-        result = complete_require_path(@target, @preposing, @postposing)
+    def completion_candidates(preposing, target, postposing, bind:)
+      if preposing && postposing
+        result = complete_require_path(target, preposing, postposing)
         return result if result
       end
-      retrieve_completion_data(@target, bind: @binding, doc_namespace: false).compact.map{ |i| i.encode(Encoding.default_external) }
+      retrieve_completion_data(target, bind: bind, doc_namespace: false).compact.map{ |i| i.encode(Encoding.default_external) }
     end
 
-    def doc_namespace(target)
-      retrieve_completion_data(target, bind: @binding, doc_namespace: true)
+    def doc_namespace(_preposing, matched, _postposing, bind:)
+      retrieve_completion_data(matched, bind: bind, doc_namespace: true)
     end
 
     def retrieve_completion_data(input, bind:, doc_namespace:)
diff --git a/lib/irb/input-method.rb b/lib/irb/input-method.rb
index 07605ca5d..af2b4994f 100644
--- a/lib/irb/input-method.rb
+++ b/lib/irb/input-method.rb
@@ -188,7 +188,7 @@ def initialize
       Readline.completion_append_character = nil
       Readline.completion_proc = ->(target) {
         bind = IRB.conf[:MAIN_CONTEXT].workspace.binding
-        RegexpCompletor.new(target, '', '', bind: bind).completion_candidates
+        RegexpCompletor.new.completion_candidates('', target, '', bind: bind)
       }
     end
 
@@ -235,14 +235,15 @@ def initialize
       super
 
       @eof = false
+      @completor = RegexpCompletor.new
 
       Reline.basic_word_break_characters = BASIC_WORD_BREAK_CHARACTERS
       Reline.completion_append_character = nil
       Reline.completer_quote_characters = ''
       Reline.completion_proc = ->(target, preposing, postposing) {
         bind = IRB.conf[:MAIN_CONTEXT].workspace.binding
-        @completor = RegexpCompletor.new(target, preposing, postposing, bind: bind)
-        @completor.completion_candidates
+        @completion_params = [preposing, target, postposing, bind]
+        @completor.completion_candidates(preposing, target, postposing, bind: bind)
       }
       Reline.output_modifier_proc =
         if IRB.conf[:USE_COLORIZE]
@@ -281,7 +282,10 @@ def auto_indent(&block)
     end
 
     def show_doc_dialog_proc
-      get_current_completor = -> { @completor }
+      doc_namespace = ->(matched) {
+        preposing, _target, postposing, bind = @completion_params
+        @completor.doc_namespace(preposing, matched, postposing, bind: bind)
+      }
       ->() {
         dialog.trap_key = nil
         alt_d = [
@@ -297,8 +301,7 @@ def show_doc_dialog_proc
         cursor_pos_to_render, result, pointer, autocomplete_dialog = context.pop(4)
         return nil if result.nil? or pointer.nil? or pointer < 0
 
-        completor = get_current_completor.call
-        name = completor.doc_namespace(result[pointer])
+        name = doc_namespace.call(result[pointer])
 
         options = {}
         options[:extra_doc_dirs] = IRB.conf[:EXTRA_DOC_DIRS] unless IRB.conf[:EXTRA_DOC_DIRS].empty?
@@ -391,7 +394,8 @@ def display_document(matched, driver: nil)
         return
       end
 
-      namespace = @completor.doc_namespace(matched)
+      _target, preposing, postposing, bind = @completion_params
+      namespace = @completor.doc_namespace(preposing, matched, postposing, bind: bind)
       return unless namespace
 
       driver ||= RDoc::RI::Driver.new
diff --git a/test/irb/test_completion.rb b/test/irb/test_completion.rb
index ad3ef3acf..2ef893826 100644
--- a/test/irb/test_completion.rb
+++ b/test/irb/test_completion.rb
@@ -16,13 +16,11 @@ def teardown
     end
 
     def completion_candidates(target, bind)
-      completor = IRB::RegexpCompletor.new(target, '', '', bind: bind)
-      completor.completion_candidates
+      IRB::RegexpCompletor.new.completion_candidates('', target, '', bind: bind)
     end
 
     def doc_namespace(target, bind)
-      completor = IRB::RegexpCompletor.new(target, '', '', bind: bind)
-      completor.doc_namespace(target)
+      IRB::RegexpCompletor.new.doc_namespace('', target, '', bind: bind)
     end
 
     class MethodCompletionTest < CompletionTest
@@ -81,12 +79,12 @@ def test_complete_class
 
     class RequireComepletionTest < CompletionTest
       def test_complete_require
-        candidates = IRB::RegexpCompletor.new("'irb", "require ", "", bind: binding).completion_candidates
+        candidates = IRB::RegexpCompletor.new.completion_candidates("require ", "'irb", "", bind: binding)
         %w['irb/init 'irb/ruby-lex].each do |word|
           assert_include candidates, word
         end
         # Test cache
-        candidates = IRB::RegexpCompletor.new("'irb", "require ", "", bind: binding).completion_candidates
+        candidates = IRB::RegexpCompletor.new.completion_candidates("require ", "'irb", "", bind: binding)
         %w['irb/init 'irb/ruby-lex].each do |word|
           assert_include candidates, word
         end
@@ -98,7 +96,7 @@ def test_complete_require_with_pathname_in_load_path
         test_path = Pathname.new(temp_dir)
         $LOAD_PATH << test_path
 
-        candidates = IRB::RegexpCompletor.new("'foo", "require ", "", bind: binding).completion_candidates
+        candidates = IRB::RegexpCompletor.new.completion_candidates("require ", "'foo", "", bind: binding)
         assert_include candidates, "'foo"
       ensure
         $LOAD_PATH.pop if test_path
@@ -112,7 +110,7 @@ def test_complete_require_with_string_convertable_in_load_path
         object.define_singleton_method(:to_s) { temp_dir }
         $LOAD_PATH << object
 
-        candidates = IRB::RegexpCompletor.new("'foo", "require ", "", bind: binding).completion_candidates
+        candidates = IRB::RegexpCompletor.new.completion_candidates("require ", "'foo", "", bind: binding)
         assert_include candidates, "'foo"
       ensure
         $LOAD_PATH.pop if object
@@ -125,27 +123,27 @@ def object.to_s; raise; end
         $LOAD_PATH << object
 
         assert_nothing_raised do
-          IRB::RegexpCompletor.new("'foo", "require ", "", bind: binding).completion_candidates
+          IRB::RegexpCompletor.new.completion_candidates("require ", "'foo", "", bind: binding)
         end
       ensure
         $LOAD_PATH.pop if object
       end
 
       def test_complete_require_library_name_first
-        candidates = IRB::RegexpCompletor.new("'csv", "require ", "", bind: binding).completion_candidates
+        candidates = IRB::RegexpCompletor.new.completion_candidates("require ", "'csv", "", bind: binding)
         assert_equal "'csv", candidates.first
       end
 
       def test_complete_require_relative
         candidates = Dir.chdir(__dir__ + "/../..") do
-          IRB::RegexpCompletor.new("'lib/irb", "require_relative ", "", bind: binding).completion_candidates
+          IRB::RegexpCompletor.new.completion_candidates("require_relative ", "'lib/irb", "", bind: binding)
         end
         %w['lib/irb/init 'lib/irb/ruby-lex].each do |word|
           assert_include candidates, word
         end
         # Test cache
         candidates = Dir.chdir(__dir__ + "/../..") do
-          IRB::RegexpCompletor.new("'lib/irb", "require_relative ", "", bind: binding).completion_candidates
+          IRB::RegexpCompletor.new.completion_candidates("require_relative ", "'lib/irb", "", bind: binding)
         end
         %w['lib/irb/init 'lib/irb/ruby-lex].each do |word|
           assert_include candidates, word
diff --git a/test/irb/test_input_method.rb b/test/irb/test_input_method.rb
index 73d3fafa3..2d8cfadcf 100644
--- a/test/irb/test_input_method.rb
+++ b/test/irb/test_input_method.rb
@@ -89,10 +89,8 @@ def setup
     end
 
     def display_document(target, bind)
-      completor = IRB::RegexpCompletor.new(target, '', '', bind: bind)
       input_method = IRB::RelineInputMethod.new
-      # @completor needs to be initialized before calling display_document
-      input_method.instance_variable_set(:@completor, completor)
+      input_method.instance_variable_set(:@completion_params, [target, '', '', bind])
       input_method.display_document(target, driver: @driver)
     end