diff --git a/ChangeLog b/ChangeLog
index a606674285..bdef1013ef 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Aug 13 22:48:39 2010  Tanaka Akira  <akr@fsij.org>
+
+	* ext/pathname/pathname.c (path_truncate): Pathname#truncate translated
+	  from pathname.rb.
+
 Fri Aug 13 16:11:36 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* lib/test/unit.rb (MiniTest::Unit.new): extend before initialize.
diff --git a/ext/pathname/lib/pathname.rb b/ext/pathname/lib/pathname.rb
index 035204e650..d1a7b5c856 100644
--- a/ext/pathname/lib/pathname.rb
+++ b/ext/pathname/lib/pathname.rb
@@ -512,9 +512,6 @@ end
 
 class Pathname    # * File *
 
-  # See <tt>File.truncate</tt>.  Truncate the file to +length+ bytes.
-  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
 
diff --git a/ext/pathname/pathname.c b/ext/pathname/pathname.c
index f98093ff87..a1d260f3ad 100644
--- a/ext/pathname/pathname.c
+++ b/ext/pathname/pathname.c
@@ -405,6 +405,15 @@ path_make_symlink(VALUE self, VALUE old)
     return rb_funcall(rb_cFile, rb_intern("symlink"), 2, old, get_strpath(self));
 }
 
+/*
+ * See <tt>File.truncate</tt>.  Truncate the file to +length+ bytes.
+ */
+static VALUE
+path_truncate(VALUE self, VALUE length)
+{
+    return rb_funcall(rb_cFile, rb_intern("truncate"), 2, get_strpath(self), length);
+}
+
 /*
  * == Pathname
  *
@@ -622,4 +631,5 @@ Init_pathname()
     rb_define_method(rb_cPathname, "stat", path_stat, 0);
     rb_define_method(rb_cPathname, "lstat", path_lstat, 0);
     rb_define_method(rb_cPathname, "make_symlink", path_make_symlink, 1);
+    rb_define_method(rb_cPathname, "truncate", path_truncate, 1);
 }