diff --git a/ChangeLog b/ChangeLog
index faeccaef17..cf98d7db3a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Aug 19 10:06:08 2010  Tanaka Akira  <akr@fsij.org>
+
+	* ext/pathname/pathname.c (path_extname): Pathname#extname translated
+	  from pathname.rb.
+
 Thu Aug 19 06:03:27 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* vm_insnhelper.c (vm_push_frame): initialize block_iseq.  a patch
diff --git a/ext/pathname/lib/pathname.rb b/ext/pathname/lib/pathname.rb
index 487402c21b..54b06eefbc 100644
--- a/ext/pathname/lib/pathname.rb
+++ b/ext/pathname/lib/pathname.rb
@@ -512,9 +512,6 @@ end
 
 class Pathname    # * File *
 
-  # See <tt>File.extname</tt>.  Returns the file's extension.
-  def extname() File.extname(@path) end
-
   # See <tt>File.expand_path</tt>.
   def expand_path(*args) self.class.new(File.expand_path(@path, *args)) end
 
diff --git a/ext/pathname/pathname.c b/ext/pathname/pathname.c
index e548ac56f5..834fa446da 100644
--- a/ext/pathname/pathname.c
+++ b/ext/pathname/pathname.c
@@ -449,6 +449,16 @@ path_dirname(VALUE self)
     return rb_class_new_instance(1, &str, rb_obj_class(self));
 }
 
+/*
+ * See <tt>File.extname</tt>.  Returns the file's extension.
+ */
+static VALUE
+path_extname(VALUE self)
+{
+    VALUE str = get_strpath(self);
+    return rb_funcall(rb_cFile, rb_intern("extname"), 1, str);
+}
+
 /*
  * == Pathname
  *
@@ -670,4 +680,5 @@ Init_pathname()
     rb_define_method(rb_cPathname, "utime", path_utime, 2);
     rb_define_method(rb_cPathname, "basename", path_basename, -1);
     rb_define_method(rb_cPathname, "dirname", path_dirname, 0);
+    rb_define_method(rb_cPathname, "extname", path_extname, 0);
 }