diff -Nur a/lib/tzinfo/ruby_core_support.rb b/lib/tzinfo/ruby_core_support.rb
--- a/lib/tzinfo/ruby_core_support.rb	2022-02-18 13:30:12.167937090 +0800
+++ b/lib/tzinfo/ruby_core_support.rb	2022-02-18 13:27:08.880845143 +0800
@@ -137,10 +137,40 @@
       def self.open_file(file_name, mode, opts, &block)
         File.open(file_name, mode, &block)
       end
-    else
+    elsif RUBY_VERSION =~ /\A1\.9\./
       def self.open_file(file_name, mode, opts, &block)
         File.open(file_name, mode, opts, &block)
       end
+    else
+      # Evaluate method as a string because **opts isn't valid syntax prior to
+      # Ruby 2.0.
+      eval(<<-EOF
+        def self.open_file(file_name, mode, opts, &block)
+          File.open(file_name, mode, **opts, &block)
+        end
+      EOF
+      )
+    end
+
+
+    # Object#untaint is a deprecated no-op in Ruby >= 2.7 and will be removed in
+    # 3.0. Add a refinement to either silence the warning, or supply the method
+    # if needed.
+    old_verbose = $VERBOSE
+    $VERBOSE = false
+    begin
+      o = Object.new
+      if [:taint, :untaint, :tainted?].none? {|m| o.respond_to?(m) } || !o.taint.tainted?
+        module UntaintExt
+          refine Object do
+            def untaint
+              self
+            end
+          end
+        end
+      end
+    ensure
+      $VERBOSE = old_verbose
     end
   end
 end
diff -Nur a/lib/tzinfo/ruby_data_source.rb b/lib/tzinfo/ruby_data_source.rb
--- a/lib/tzinfo/ruby_data_source.rb	2022-02-18 13:30:12.167937090 +0800
+++ b/lib/tzinfo/ruby_data_source.rb	2022-02-18 13:26:53.348583123 +0800
@@ -1,4 +1,6 @@
 module TZInfo
+  using RubyCoreSupport::UntaintExt if RubyCoreSupport.const_defined?(:UntaintExt)
+
   # A DataSource that loads data from the set of Ruby modules included in the
   # TZInfo::Data library (tzinfo-data gem).
   #
diff -Nur a/lib/tzinfo/zoneinfo_data_source.rb b/lib/tzinfo/zoneinfo_data_source.rb
--- a/lib/tzinfo/zoneinfo_data_source.rb	2022-02-18 13:30:12.171937158 +0800
+++ b/lib/tzinfo/zoneinfo_data_source.rb	2022-02-18 13:26:53.348583123 +0800
@@ -1,4 +1,6 @@
 module TZInfo
+  using RubyCoreSupport::UntaintExt if RubyCoreSupport.const_defined?(:UntaintExt)
+
   # An InvalidZoneinfoDirectory exception is raised if the DataSource is
   # set to a specific zoneinfo path, which is not a valid zoneinfo directory
   # (i.e. a directory containing index files named iso3166.tab and zone.tab
diff -Nur a/lib/tzinfo/zoneinfo_timezone_info.rb b/lib/tzinfo/zoneinfo_timezone_info.rb
--- a/lib/tzinfo/zoneinfo_timezone_info.rb	2022-02-18 13:30:12.171937158 +0800
+++ b/lib/tzinfo/zoneinfo_timezone_info.rb	2022-02-18 13:26:53.348583123 +0800
@@ -1,4 +1,6 @@
 module TZInfo
+  using RubyCoreSupport::UntaintExt if RubyCoreSupport.const_defined?(:UntaintExt)
+
   # An InvalidZoneinfoFile exception is raised if an attempt is made to load an
   # invalid zoneinfo file.
   class InvalidZoneinfoFile < StandardError
diff -Nur a/test/tc_country.rb b/test/tc_country.rb
--- a/test/tc_country.rb	2022-02-18 13:30:12.171937158 +0800
+++ b/test/tc_country.rb	2022-02-18 13:26:53.348583123 +0800
@@ -2,6 +2,8 @@
 
 include TZInfo
 
+using TaintExt if Module.const_defined?(:TaintExt)
+
 class TCCountry < Minitest::Test
   def setup
     @orig_data_source = DataSource.get
@@ -46,7 +48,7 @@
   def test_get_tainted_loaded
     Country.get('GB')
   
-    safe_test do
+    safe_test(:unavailable => :skip) do
       code = 'GB'.dup.taint
       assert(code.tainted?)
       country = Country.get(code)
@@ -65,7 +67,7 @@
   end
   
   def test_get_tainted_not_previously_loaded
-    safe_test do
+    safe_test(:unavailable => :skip) do
       code = 'GB'.dup.taint
       assert(code.tainted?)
       country = Country.get(code)
diff -Nur a/test/tc_ruby_data_source.rb b/test/tc_ruby_data_source.rb
--- a/test/tc_ruby_data_source.rb	2022-02-18 13:30:12.179937293 +0800
+++ b/test/tc_ruby_data_source.rb	2022-02-18 13:28:17.321999706 +0800
@@ -2,6 +2,8 @@
 
 include TZInfo
 
+using TaintExt if Module.const_defined?(:TaintExt)
+
 class TCRubyDataSource < Minitest::Test
   def setup
     @data_source = RubyDataSource.new
@@ -55,7 +57,8 @@
   end
 
   def test_load_timezone_info_tainted
-    safe_test do
+
+    safe_test(:unavailable => :skip) do
       identifier = 'Europe/Amsterdam'.dup.taint
       assert(identifier.tainted?)
       info = @data_source.load_timezone_info(identifier)
@@ -119,7 +123,7 @@
   end
   
   def test_load_country_info_tainted
-    safe_test do
+    safe_test(:unavailable => :skip) do
       code = 'NL'.dup.taint
       assert(code.tainted?)
       info = @data_source.load_country_info(code)
diff -Nur a/test/tc_timezone.rb b/test/tc_timezone.rb
--- a/test/tc_timezone.rb	2022-02-18 13:30:12.179937293 +0800
+++ b/test/tc_timezone.rb	2022-02-18 13:28:41.098400800 +0800
@@ -2,6 +2,8 @@
 
 include TZInfo
 
+using TaintExt if Module.const_defined?(:TaintExt)
+
 class TCTimezone < Minitest::Test
 
   class BlockCalled < StandardError
@@ -242,7 +244,7 @@
   def test_get_tainted_loaded
     Timezone.get('Europe/Andorra')
   
-    safe_test do
+    safe_test(:unavailable => :skip) do
       identifier = 'Europe/Andorra'.dup.taint
       assert(identifier.tainted?)
       tz = Timezone.get(identifier)
@@ -261,7 +263,8 @@
   end
   
   def test_get_tainted_not_previously_loaded
-    safe_test do
+
+    safe_test(:unavailable => :skip) do
       identifier = 'Europe/Andorra'.dup.taint
       assert(identifier.tainted?)
       tz = Timezone.get(identifier)
diff -Nur a/test/tc_zoneinfo_data_source.rb b/test/tc_zoneinfo_data_source.rb
--- a/test/tc_zoneinfo_data_source.rb	2022-02-18 13:30:12.183937360 +0800
+++ b/test/tc_zoneinfo_data_source.rb	2022-02-18 13:26:53.348583123 +0800
@@ -7,6 +7,9 @@
 
 include TZInfo
 
+using RubyCoreSupport::UntaintExt if RubyCoreSupport.const_defined?(:UntaintExt)
+using TaintExt if Module.const_defined?(:TaintExt)
+
 class TCZoneinfoDataSource < Minitest::Test
   ZONEINFO_DIR = File.join(File.expand_path(File.dirname(__FILE__)), 'zoneinfo').untaint
   
@@ -653,7 +656,7 @@
   end
 
   def test_load_timezone_info_tainted
-    safe_test do
+    safe_test(:unavailable => :skip) do
       identifier = 'Europe/Amsterdam'.dup.taint
       assert(identifier.tainted?)
       info = @data_source.load_timezone_info(identifier)
@@ -840,7 +843,7 @@
   end
   
   def test_load_country_info_tainted
-    safe_test do
+    safe_test(:unavailable => :skip) do
       code = 'NL'.dup.taint
       assert(code.tainted?)
       info = @data_source.load_country_info(code)
diff -Nur a/test/tc_zoneinfo_timezone_info.rb b/test/tc_zoneinfo_timezone_info.rb
--- a/test/tc_zoneinfo_timezone_info.rb	2022-02-18 13:30:12.183937360 +0800
+++ b/test/tc_zoneinfo_timezone_info.rb	2022-02-18 13:26:53.348583123 +0800
@@ -5,6 +5,8 @@
 
 include TZInfo
 
+using RubyCoreSupport::UntaintExt if RubyCoreSupport.const_defined?(:UntaintExt)
+
 class TCZoneinfoTimezoneInfo < Minitest::Test
 
   begin
diff -Nur a/test/test_utils.rb b/test/test_utils.rb
--- a/test/test_utils.rb	2022-02-18 13:30:12.187937428 +0800
+++ b/test/test_utils.rb	2022-02-18 13:29:32.443266958 +0800
@@ -1,4 +1,6 @@
-TESTS_DIR = File.expand_path(File.dirname(__FILE__)).untaint
+tests_dir = File.expand_path(File.dirname(__FILE__))
+tests_dir.untaint if RUBY_VERSION < '2.7'
+TESTS_DIR = tests_dir
 TZINFO_LIB_DIR = File.expand_path(File.join(TESTS_DIR, '..', 'lib'))
 TZINFO_TEST_DATA_DIR = File.join(TESTS_DIR, 'tzinfo-data')
 TZINFO_TEST_ZONEINFO_DIR = File.join(TESTS_DIR, 'zoneinfo')
@@ -55,8 +57,8 @@
   end
   
   def safe_test(options = {})
-    # JRuby and Rubinus don't support SAFE levels.
-    available = !(defined?(RUBY_ENGINE) && %w(jruby rbx).include?(RUBY_ENGINE))
+    # Ruby >= 2.7, JRuby and Rubinus don't support SAFE levels.
+    available = RUBY_VERSION < '2.7' && !(defined?(RUBY_ENGINE) && %w(jruby rbx).include?(RUBY_ENGINE))
    
     if available || options[:unavailable] != :skip
       thread = Thread.new do
@@ -150,6 +152,19 @@
     end
   end
 end
+
+
+# Object#taint is a deprecated no-op in Ruby 2.7 and outputs a warning. It will
+# be removed in 3.0. Silence the warning or supply a replacement.
+if TZInfo::RubyCoreSupport.const_defined?(:UntaintExt)
+  module TaintExt
+    refine Object do
+      def taint
+        self
+      end
+    end
+  end
+end
 
 
 # JRuby 1.7.5 to 1.7.9 consider DateTime instances that differ by less than 
diff -Nur a/test/ts_all_zoneinfo.rb b/test/ts_all_zoneinfo.rb
--- a/test/ts_all_zoneinfo.rb	2022-02-18 13:30:12.187937428 +0800
+++ b/test/ts_all_zoneinfo.rb	2022-02-18 13:26:53.348583123 +0800
@@ -2,6 +2,8 @@
 
 # Use a zoneinfo directory containing files needed by the tests.
 # The symlinks in this directory are set up in test_utils.rb.
-TZInfo::DataSource.set(:zoneinfo, File.join(File.expand_path(File.dirname(__FILE__)), 'zoneinfo').untaint)
+zoneinfo_path = File.join(File.expand_path(File.dirname(__FILE__)), 'zoneinfo')
+zoneinfo_path.untaint if RUBY_VERSION < '2.7'
+TZInfo::DataSource.set(:zoneinfo, zoneinfo_path)
 
 require File.join(File.expand_path(File.dirname(__FILE__)), 'ts_all.rb')