diff --git a/test/dbm/test_dbm.rb b/test/dbm/test_dbm.rb
index 93198fdea2..874b326404 100644
--- a/test/dbm/test_dbm.rb
+++ b/test/dbm/test_dbm.rb
@@ -47,6 +47,8 @@ if defined? DBM
     end
 
     def test_delete_rdonly
+      skip("skipped because root can read anything") if Process.uid == 0
+
       if /^CYGWIN_9/ !~ SYSTEM
         assert_raise(DBMError) {
           @dbm_rdonly.delete("foo")
diff --git a/test/gdbm/test_gdbm.rb b/test/gdbm/test_gdbm.rb
index 1d69634f88..9e97eb3587 100644
--- a/test/gdbm/test_gdbm.rb
+++ b/test/gdbm/test_gdbm.rb
@@ -43,6 +43,8 @@ if defined? GDBM
     end
 
     def test_delete_rdonly
+      skip("skipped because root can open anything") if Process.uid == 0
+
       if /^CYGWIN_9/ !~ SYSTEM
         assert_raise(GDBMError) {
           @gdbm_rdonly.delete("foo")
@@ -211,6 +213,8 @@ if defined? GDBM
     end if defined? GDBM::NOLOCK # gdbm 1.8.0 specific
 
     def test_s_open_error
+    skip if Process.uid == 0 # because root can open anything
+
       assert_instance_of(GDBM, gdbm = GDBM.open("#{@tmpdir}/#{@prefix}", 0))
       assert_raise(Errno::EACCES, Errno::EWOULDBLOCK) {
         GDBM.open("#{@tmpdir}/#{@prefix}", 0)
diff --git a/test/irb/test_workspace.rb b/test/irb/test_workspace.rb
index 0dd46175c8..0795b17e09 100644
--- a/test/irb/test_workspace.rb
+++ b/test/irb/test_workspace.rb
@@ -34,6 +34,7 @@ module TestIRB
 
     def test_code_around_binding_with_existing_unreadable_file
       skip 'chmod cannot make file unreadable on windows' if windows?
+      skip 'skipped in root privilege' if Process.uid == 0
 
       Tempfile.create do |f|
         code = "IRB::WorkSpace.new(binding)\n"
diff --git a/test/pathname/test_pathname.rb b/test/pathname/test_pathname.rb
index ad104d06df..8a72b8026d 100644
--- a/test/pathname/test_pathname.rb
+++ b/test/pathname/test_pathname.rb
@@ -1336,6 +1336,7 @@ class TestPathname < Test::Unit::TestCase
         assert_equal([Pathname("d"), Pathname("d/x")], a)
 
         skip "no meaning test on Windows" if /mswin|mingw/ =~ RUBY_PLATFORM
+        skip 'skipped in root privilege' if Process.uid == 0
         a = [];
         assert_raise_with_message(Errno::EACCES, %r{d/x}) do
           Pathname(".").find(ignore_error: false) {|v| a << v }
diff --git a/test/rdoc/test_rdoc_options.rb b/test/rdoc/test_rdoc_options.rb
index 760cf9db55..400ed9a549 100644
--- a/test/rdoc/test_rdoc_options.rb
+++ b/test/rdoc/test_rdoc_options.rb
@@ -18,6 +18,7 @@ class TestRDocOptions < RDoc::TestCase
 
   def test_check_files
     skip "assumes UNIX permission model" if /mswin|mingw/ =~ RUBY_PLATFORM
+    skip "skipped in root privilege" if Process.uid == 0
 
     out, err = capture_io do
       temp_dir do
diff --git a/test/rdoc/test_rdoc_rdoc.rb b/test/rdoc/test_rdoc_rdoc.rb
index 3244238e3c..bd4794342c 100644
--- a/test/rdoc/test_rdoc_rdoc.rb
+++ b/test/rdoc/test_rdoc_rdoc.rb
@@ -296,6 +296,7 @@ class TestRDocRDoc < RDoc::TestCase
 
   def test_parse_file_forbidden
     skip 'chmod not supported' if Gem.win_platform?
+    skip 'skipped in root privilege' if Process.uid == 0
 
     @rdoc.store = RDoc::Store.new
 
diff --git a/test/rdoc/test_rdoc_rubygems_hook.rb b/test/rdoc/test_rdoc_rubygems_hook.rb
index 2fb79ff577..2664b35cbb 100644
--- a/test/rdoc/test_rdoc_rubygems_hook.rb
+++ b/test/rdoc/test_rdoc_rubygems_hook.rb
@@ -200,6 +200,7 @@ class TestRDocRubygemsHook < Gem::TestCase
 
   def test_remove_unwritable
     skip 'chmod not supported' if Gem.win_platform?
+    skip 'skipped in root privilege' if Process.uid == 0
     FileUtils.mkdir_p @a.base_dir
     FileUtils.chmod 0, @a.base_dir
 
@@ -228,6 +229,7 @@ class TestRDocRubygemsHook < Gem::TestCase
 
   def test_setup_unwritable
     skip 'chmod not supported' if Gem.win_platform?
+    skip 'skipped in root privilege' if Process.uid == 0
     FileUtils.mkdir_p @a.doc_dir
     FileUtils.chmod 0, @a.doc_dir
 
diff --git a/test/rubygems/test_gem.rb b/test/rubygems/test_gem.rb
index 8a11cc2ecf..3b08e61374 100644
--- a/test/rubygems/test_gem.rb
+++ b/test/rubygems/test_gem.rb
@@ -463,7 +463,7 @@ class TestGem < Gem::TestCase
     assert File.directory?(util_cache_dir)
   end
 
-  unless win_platform? then # only for FS that support write protection
+  unless win_platform? || Process.uid == 0 then # only for FS that support write protection
     def test_self_ensure_gem_directories_write_protected
       gemdir = File.join @tempdir, "egd"
       FileUtils.rm_r gemdir rescue nil
diff --git a/test/rubygems/test_gem_commands_cleanup_command.rb b/test/rubygems/test_gem_commands_cleanup_command.rb
index c55e195975..a222659ead 100644
--- a/test/rubygems/test_gem_commands_cleanup_command.rb
+++ b/test/rubygems/test_gem_commands_cleanup_command.rb
@@ -158,7 +158,7 @@ class TestGemCommandsCleanupCommand < Gem::TestCase
     assert_path_exists @a_1_1.gem_dir
   ensure
     FileUtils.chmod 0755, @gemhome
-  end unless win_platform?
+  end unless win_platform? || Process.uid == 0
 
   def test_execute_dry_run
     @cmd.options[:args] = %w[a]
diff --git a/test/rubygems/test_gem_commands_install_command.rb b/test/rubygems/test_gem_commands_install_command.rb
index dd86a85038..fefc5c7059 100644
--- a/test/rubygems/test_gem_commands_install_command.rb
+++ b/test/rubygems/test_gem_commands_install_command.rb
@@ -131,6 +131,7 @@ class TestGemCommandsInstallCommand < Gem::TestCase
 
   def test_execute_no_user_install
     skip 'skipped on MS Windows (chmod has no effect)' if win_platform?
+    skip 'skipped in root privilege' if Process.uid == 0
 
     specs = spec_fetcher do |fetcher|
       fetcher.gem 'a', 2
diff --git a/test/rubygems/test_gem_install_update_options.rb b/test/rubygems/test_gem_install_update_options.rb
index e2d546307d..69a2b61041 100644
--- a/test/rubygems/test_gem_install_update_options.rb
+++ b/test/rubygems/test_gem_install_update_options.rb
@@ -141,6 +141,8 @@ class TestGemInstallUpdateOptions < Gem::InstallerTestCase
   def test_user_install_disabled_read_only
     if win_platform?
       skip('test_user_install_disabled_read_only test skipped on MS Windows')
+    elsif Process.uid == 0
+      skip('test_user_install_disabled_read_only test skipped in root privilege')
     else
       @cmd.handle_options %w[--no-user-install]
 
diff --git a/test/rubygems/test_gem_installer.rb b/test/rubygems/test_gem_installer.rb
index 39095c7dee..63acc3d130 100644
--- a/test/rubygems/test_gem_installer.rb
+++ b/test/rubygems/test_gem_installer.rb
@@ -437,6 +437,8 @@ gem 'other', version
 
     if win_platform?
       skip('test_generate_bin_script_no_perms skipped on MS Windows')
+    elsif Process.uid == 0
+      skip('test_generate_bin_script_no_perms skipped in root privilege')
     else
       FileUtils.chmod 0000, util_inst_bindir
 
@@ -529,6 +531,8 @@ gem 'other', version
 
     if win_platform?
       skip('test_generate_bin_symlink_no_perms skipped on MS Windows')
+    elsif Process.uid == 0
+      skip('test_user_install_disabled_read_only test skipped in root privilege')
     else
       FileUtils.chmod 0000, util_inst_bindir
 
diff --git a/test/rubygems/test_gem_rdoc.rb b/test/rubygems/test_gem_rdoc.rb
index 76ca8c45a9..3961a8e3f9 100644
--- a/test/rubygems/test_gem_rdoc.rb
+++ b/test/rubygems/test_gem_rdoc.rb
@@ -223,6 +223,7 @@ class TestGemRDoc < Gem::TestCase
 
   def test_remove_unwritable
     skip 'chmod not supported' if Gem.win_platform?
+    skip 'skipped in root privilege' if Process.uid == 0
     FileUtils.mkdir_p @a.base_dir
     FileUtils.chmod 0, @a.base_dir
 
@@ -251,6 +252,7 @@ class TestGemRDoc < Gem::TestCase
 
   def test_setup_unwritable
     skip 'chmod not supported' if Gem.win_platform?
+    skip 'skipped in root privilege' if Process.uid == 0
     FileUtils.mkdir_p @a.doc_dir
     FileUtils.chmod 0, @a.doc_dir
 
diff --git a/test/rubygems/test_gem_remote_fetcher.rb b/test/rubygems/test_gem_remote_fetcher.rb
index ee5ac77717..fc51b06f1b 100644
--- a/test/rubygems/test_gem_remote_fetcher.rb
+++ b/test/rubygems/test_gem_remote_fetcher.rb
@@ -431,7 +431,7 @@ PeIQQkFng2VVot/WAQbv3ePqWq07g1BBcwIBAg==
     assert File.exist?(a1_cache_gem)
   end
 
-  unless win_platform? # File.chmod doesn't work
+  unless win_platform? || Process.uid == 0 # File.chmod doesn't work
     def test_download_local_read_only
       FileUtils.mv @a1_gem, @tempdir
       local_path = File.join @tempdir, @a1.file_name
diff --git a/test/rubygems/test_gem_specification.rb b/test/rubygems/test_gem_specification.rb
index bb6acbc7de..77e4d7122d 100644
--- a/test/rubygems/test_gem_specification.rb
+++ b/test/rubygems/test_gem_specification.rb
@@ -1461,6 +1461,7 @@ dependencies: []
 
   def test_build_extensions_extensions_dir_unwritable
     skip 'chmod not supported' if Gem.win_platform?
+    skip 'skipped in root privilege' if Process.uid == 0
 
     ext_spec
 
@@ -1486,7 +1487,7 @@ dependencies: []
     @ext.build_extensions
     refute_path_exists @ext.extension_dir
   ensure
-    unless ($DEBUG or win_platform?) then
+    unless ($DEBUG or win_platform? or Process.uid == 0) then
       FileUtils.chmod 0755, File.join(@ext.base_dir, 'extensions')
       FileUtils.chmod 0755, @ext.base_dir
     end
diff --git a/test/rubygems/test_require.rb b/test/rubygems/test_require.rb
index a846f46833..a106fc21a6 100644
--- a/test/rubygems/test_require.rb
+++ b/test/rubygems/test_require.rb
@@ -38,18 +38,6 @@ class TestGemRequire < Gem::TestCase
     assert require(path), "'#{path}' was already required"
   end
 
-  def append_latch spec
-    dir = spec.gem_dir
-    Dir.chdir dir do
-      spec.files.each do |file|
-        File.open file, 'a' do |fp|
-          fp.puts "FILE_ENTERED_LATCH.release"
-          fp.puts "FILE_EXIT_LATCH.await"
-        end
-      end
-    end
-  end
-
   # Providing -I on the commandline should always beat gems
   def test_dash_i_beats_gems
     a1 = new_spec "a", "1", {"b" => "= 1"}, "lib/test_gem_require_a.rb"
@@ -80,6 +68,15 @@ class TestGemRequire < Gem::TestCase
     Object.send :remove_const, :HELLO if Object.const_defined? :HELLO
   end
 
+  def create_sync_thread
+    Thread.new do
+      yield
+    ensure
+      FILE_ENTERED_LATCH.release
+      FILE_EXIT_LATCH.await
+    end
+  end
+
   def test_concurrent_require
     skip 'deadlock' if /^1\.8\./ =~ RUBY_VERSION
 
@@ -91,11 +88,8 @@ class TestGemRequire < Gem::TestCase
 
     install_specs a1, b1
 
-    append_latch a1
-    append_latch b1
-
-    t1 = Thread.new { assert_require 'a' }
-    t2 = Thread.new { assert_require 'b' }
+    t1 = create_sync_thread{ assert_require 'a' }
+    t2 = create_sync_thread{ assert_require 'b' }
 
     # wait until both files are waiting on the exit latch
     FILE_ENTERED_LATCH.await
@@ -106,8 +100,6 @@ class TestGemRequire < Gem::TestCase
     assert t1.join, "thread 1 should exit"
     assert t2.join, "thread 2 should exit"
   ensure
-    return if $! # skipping
-
     Object.send :remove_const, :FILE_ENTERED_LATCH
     Object.send :remove_const, :FILE_EXIT_LATCH
   end
diff --git a/test/sdbm/test_sdbm.rb b/test/sdbm/test_sdbm.rb
index 7b2d39c9a1..6cea36d3a5 100644
--- a/test/sdbm/test_sdbm.rb
+++ b/test/sdbm/test_sdbm.rb
@@ -108,6 +108,7 @@ class TestSDBM < Test::Unit::TestCase
 
   def test_s_open_error
     skip "doesn't support to avoid read access by owner on Windows" if /mswin|mingw/ =~ RUBY_PLATFORM
+    skip "skipped because root can open anything" if Process.uid == 0
     assert_instance_of(SDBM, sdbm = SDBM.open("#{@tmpdir}/#{@prefix}", 0))
     assert_raise(Errno::EACCES) {
       SDBM.open("#{@tmpdir}/#{@prefix}", 0)
@@ -519,6 +520,7 @@ class TestSDBM < Test::Unit::TestCase
   end
 
   def test_readonly
+    skip "skipped because root can read anything" if /mswin|mingw/ !~ RUBY_PLATFORM && Process.uid == 0
     @sdbm["bar"] = "baz"
     @sdbm.close
     File.chmod(0444, @path + ".dir")
diff --git a/test/test_find.rb b/test/test_find.rb
index d4d958859d..01b1fcc121 100644
--- a/test/test_find.rb
+++ b/test/test_find.rb
@@ -104,6 +104,8 @@ class TestFind < Test::Unit::TestCase
 
   def test_unreadable_dir
     skip "no meaning test on Windows" if /mswin|mingw/ =~ RUBY_PLATFORM
+    skip if Process.uid == 0 # because root can read anything
+
     Dir.mktmpdir {|d|
       Dir.mkdir(dir = "#{d}/dir")
       File.open("#{dir}/foo", "w"){}
@@ -157,6 +159,8 @@ class TestFind < Test::Unit::TestCase
         assert_equal([d, dir, file], a)
 
         skip "no meaning test on Windows" if /mswin|mingw/ =~ RUBY_PLATFORM
+        skip "skipped because root can read anything" if Process.uid == 0
+
         a = []
         assert_raise_with_message(Errno::EACCES, /#{Regexp.quote(file)}/) do
           Find.find(d, ignore_error: false) {|f| a << f }
diff --git a/version.h b/version.h
index f7cd4e3605..fb37d00ae7 100644
--- a/version.h
+++ b/version.h
@@ -1,10 +1,10 @@
 #define RUBY_VERSION "2.5.0"
-#define RUBY_RELEASE_DATE "2018-03-15"
-#define RUBY_PATCHLEVEL 40
+#define RUBY_RELEASE_DATE "2018-03-19"
+#define RUBY_PATCHLEVEL 41
 
 #define RUBY_RELEASE_YEAR 2018
 #define RUBY_RELEASE_MONTH 3
-#define RUBY_RELEASE_DAY 15
+#define RUBY_RELEASE_DAY 19
 
 #include "ruby/version.h"