diff --git a/lib/csv.rb b/lib/csv.rb
index 1e179f4edc17b8..65bb3fbad946c7 100644
--- a/lib/csv.rb
+++ b/lib/csv.rb
@@ -95,14 +95,11 @@
 
 require_relative "csv/fields_converter"
 require_relative "csv/input_record_separator"
-require_relative "csv/match_p"
 require_relative "csv/parser"
 require_relative "csv/row"
 require_relative "csv/table"
 require_relative "csv/writer"
 
-using CSV::MatchP if CSV.const_defined?(:MatchP)
-
 # == \CSV
 # \CSV (comma-separated variables) data is a text representation of a table:
 # - A _row_ _separator_ delimits table rows.
diff --git a/lib/csv/delete_suffix.rb b/lib/csv/delete_suffix.rb
deleted file mode 100644
index d4577189970198..00000000000000
--- a/lib/csv/delete_suffix.rb
+++ /dev/null
@@ -1,18 +0,0 @@
-# frozen_string_literal: true
-
-# This provides String#delete_suffix? for Ruby 2.4.
-unless String.method_defined?(:delete_suffix)
-  class CSV
-    module DeleteSuffix
-      refine String do
-        def delete_suffix(suffix)
-          if end_with?(suffix)
-            self[0...-suffix.size]
-          else
-            self
-          end
-        end
-      end
-    end
-  end
-end
diff --git a/lib/csv/match_p.rb b/lib/csv/match_p.rb
deleted file mode 100644
index 775559a3ebfbe6..00000000000000
--- a/lib/csv/match_p.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-# frozen_string_literal: true
-
-# This provides String#match? and Regexp#match? for Ruby 2.3.
-unless String.method_defined?(:match?)
-  class CSV
-    module MatchP
-      refine String do
-        def match?(pattern)
-          self =~ pattern
-        end
-      end
-
-      refine Regexp do
-        def match?(string)
-          self =~ string
-        end
-      end
-    end
-  end
-end
diff --git a/lib/csv/parser.rb b/lib/csv/parser.rb
index 7fe5f0d3abb9dc..9457ccab14fef6 100644
--- a/lib/csv/parser.rb
+++ b/lib/csv/parser.rb
@@ -2,15 +2,10 @@
 
 require "strscan"
 
-require_relative "delete_suffix"
 require_relative "input_record_separator"
-require_relative "match_p"
 require_relative "row"
 require_relative "table"
 
-using CSV::DeleteSuffix if CSV.const_defined?(:DeleteSuffix)
-using CSV::MatchP if CSV.const_defined?(:MatchP)
-
 class CSV
   # Note: Don't use this class directly. This is an internal class.
   class Parser
diff --git a/lib/csv/writer.rb b/lib/csv/writer.rb
index 4a9a35c5afc1ad..8cdf96c430a6af 100644
--- a/lib/csv/writer.rb
+++ b/lib/csv/writer.rb
@@ -1,11 +1,8 @@
 # frozen_string_literal: true
 
 require_relative "input_record_separator"
-require_relative "match_p"
 require_relative "row"
 
-using CSV::MatchP if CSV.const_defined?(:MatchP)
-
 class CSV
   # Note: Don't use this class directly. This is an internal class.
   class Writer