diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index ed8b613..92b03e9 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -40,3 +40,20 @@ jobs:
       run: bundle install
     - name: Run test
       run: rake compile test
+
+  spec:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ruby
+      - uses: actions/checkout@v5
+        with:
+          repository: ruby/spec
+          path: rubyspec
+      - name: Clone MSpec
+        run: git clone https://github.com/ruby/mspec.git ../mspec
+      - run: bundle install
+      - run: rake compile
+      - run: ../mspec/bin/mspec -Ilib rubyspec/library/pathname
diff --git a/ext/pathname/pathname.c b/ext/pathname/pathname.c
index 73be963..10d055f 100644
--- a/ext/pathname/pathname.c
+++ b/ext/pathname/pathname.c
@@ -3,7 +3,6 @@
 static VALUE rb_cPathname;
 static ID id_at_path;
 static ID id_sub;
-static ID id_realdirpath;
 
 static VALUE
 get_strpath(VALUE obj)
@@ -84,22 +83,6 @@ path_sub(int argc, VALUE *argv, VALUE self)
     return rb_class_new_instance(1, &str, rb_obj_class(self));
 }
 
-/*
- * Returns the real (absolute) pathname of +self+ in the actual filesystem.
- *
- * Does not contain symlinks or useless dots, +..+ and +.+.
- *
- * The last component of the real pathname can be nonexistent.
- */
-static VALUE
-path_realdirpath(int argc, VALUE *argv, VALUE self)
-{
-    VALUE basedir, str;
-    rb_scan_args(argc, argv, "01", &basedir);
-    str = rb_funcall(rb_cFile, id_realdirpath, 2, get_strpath(self), basedir);
-    return rb_class_new_instance(1, &str, rb_obj_class(self));
-}
-
 static void init_ids(void);
 
 void
@@ -119,7 +102,6 @@ InitVM_pathname(void)
     rb_cPathname = rb_define_class("Pathname", rb_cObject);
     rb_define_method(rb_cPathname, "<=>", path_cmp, 1);
     rb_define_method(rb_cPathname, "sub", path_sub, -1);
-    rb_define_method(rb_cPathname, "realdirpath", path_realdirpath, -1);
 }
 
 void
@@ -128,5 +110,4 @@ init_ids(void)
 #undef rb_intern
     id_at_path = rb_intern("@path");
     id_sub = rb_intern("sub");
-    id_realdirpath = rb_intern("realdirpath");
 }
diff --git a/lib/pathname.rb b/lib/pathname.rb
index 404be1a..a0db812 100644
--- a/lib/pathname.rb
+++ b/lib/pathname.rb
@@ -150,6 +150,7 @@ module ::Kernel
 # - #read(*args)
 # - #binread(*args)
 # - #readlines(*args)
+# - #sysopen(*args)
 # - #write(*args)
 # - #binwrite(*args)
 # - #atime
@@ -190,11 +191,6 @@ module ::Kernel
 # - #mkdir(*args)
 # - #opendir(*args)
 #
-# === IO
-#
-# This method is a facade for IO:
-# - #sysopen(*args)
-#
 # === Utilities
 #
 # These methods are a mixture of Find, FileUtils, and others:
@@ -239,9 +235,10 @@ class Pathname
   # If +path+ contains a NUL character (<tt>\0</tt>), an ArgumentError is raised.
   #
   def initialize(path)
-    path = path.to_path if path.respond_to? :to_path
-
-    raise TypeError unless path.is_a?(String) # Compatibility for C version
+    unless String === path
+      path = path.to_path if path.respond_to? :to_path
+      raise TypeError unless String === path
+    end
 
     if path.include?("\0")
       raise ArgumentError, "pathname contains \\0: #{path.inspect}"
@@ -884,11 +881,6 @@ def relative_path_from(base_directory)
   end
 end
 
-class Pathname    # * IO *
-  # See <tt>IO.sysopen</tt>.
-  def sysopen(...) IO.sysopen(@path, ...) end
-end
-
 class Pathname    # * File *
   #
   # #each_line iterates over the line in the file.  It yields a String object
@@ -911,6 +903,9 @@ def binread(...) File.binread(@path, ...) end
   # See <tt>File.readlines</tt>.  Returns all the lines from the file.
   def readlines(...) File.readlines(@path, ...) end
 
+  # See <tt>File.sysopen</tt>.
+  def sysopen(...) File.sysopen(@path, ...) end
+
   # Writes +contents+ to the file. See <tt>File.write</tt>.
   def write(...) File.write(@path, ...) end
 
@@ -986,6 +981,13 @@ def truncate(length) File.truncate(@path, length) end
   # See <tt>File.utime</tt>.  Update the access and modification times.
   def utime(atime, mtime) File.utime(atime, mtime, @path) end
 
+  # Update the access and modification times of the file.
+  #
+  # Same as Pathname#utime, but does not follow symbolic links.
+  #
+  # See File.lutime.
+  def lutime(atime, mtime) File.lutime(atime, mtime, @path) end
+
   # See <tt>File.basename</tt>.  Returns the last component of the path.
   def basename(...) self.class.new(File.basename(@path, ...)) end
 
@@ -1012,6 +1014,13 @@ def split()
   #
   # All components of the pathname must exist when this method is called.
   def realpath(...) self.class.new(File.realpath(@path, ...)) end
+
+  # Returns the real (absolute) pathname of +self+ in the actual filesystem.
+  #
+  # Does not contain symlinks or useless dots, +..+ and +.+.
+  #
+  # The last component of the real pathname can be nonexistent.
+  def realdirpath(...) self.class.new(File.realdirpath(@path, ...)) end
 end
 
 
@@ -1236,12 +1245,8 @@ module Kernel
   #
   # This method is available since 1.8.5.
   def Pathname(path) # :doc:
-    Kernel.Pathname(path)
-  end
-  private :Pathname
-
-  def self.Pathname(path) # Compatibility for C version
     return path if Pathname === path
     Pathname.new(path)
   end
+  module_function :Pathname
 end
diff --git a/test/pathname/test_pathname.rb b/test/pathname/test_pathname.rb
index 7e0011c..e80473e 100644
--- a/test/pathname/test_pathname.rb
+++ b/test/pathname/test_pathname.rb
@@ -348,7 +348,7 @@ def has_symlink?
     rescue NotImplementedError
       return false
     rescue Errno::ENOENT
-      return false
+      return true
     rescue Errno::EACCES
       return false
     end
@@ -370,10 +370,11 @@ def has_hardlink?
   end
 
   def realpath(path, basedir=nil)
-    Pathname.new(path).realpath(basedir).to_s
+    Pathname.new(path).realpath(*basedir).to_s
   end
 
   def test_realpath
+    omit "not working yet" if RUBY_ENGINE == "jruby"
     return if !has_symlink?
     with_tmpchdir('rubytest-pathname') {|dir|
       assert_raise(Errno::ENOENT) { realpath("#{dir}/not-exist") }
@@ -434,6 +435,7 @@ def realdirpath(path)
   end
 
   def test_realdirpath
+    omit "not working yet" if RUBY_ENGINE == "jruby"
     return if !has_symlink?
     Dir.mktmpdir('rubytest-pathname') {|dir|
       rdir = realpath(dir)
@@ -1054,7 +1056,11 @@ def test_lutime
       latime = Time.utc(2000)
       lmtime = Time.utc(1999)
       File.symlink("a", "l")
-      Pathname("l").utime(latime, lmtime)
+      begin
+        Pathname("l").lutime(latime, lmtime)
+      rescue NotImplementedError
+        next
+      end
       s = File.lstat("a")
       ls = File.lstat("l")
       assert_equal(atime, s.atime)