diff --git a/ChangeLog b/ChangeLog
index 214d9250d4..31a768c663 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Wed May 23 05:49:49 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/extmk.rb, ext/purelib.rb, lib/mkmf.rb, runruby.rb: clear default
+	  load path to get rid of load pre-installed extensions/libraries.
+	  [ruby-core:11017]
+
 Wed May 23 06:14:15 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* win32/win32.c (move_to_next_entry): loc also must move forward.
diff --git a/ext/extmk.rb b/ext/extmk.rb
index ac396a0d80..c3ba27aaf4 100644
--- a/ext/extmk.rb
+++ b/ext/extmk.rb
@@ -324,7 +324,11 @@ else
   $ruby = '$(topdir)/miniruby' + EXEEXT
 end
 $ruby << " -I'$(topdir)' -I'$(hdrdir)/lib'"
+$ruby << " -I'$(extout)/$(arch)' -I'$(extout)/common'" if $extout
+$ruby << " -I'$(hdrdir)/ext' -rpurelib.rb"
 $config_h = '$(topdir)/config.h'
+ENV["RUBYLIB"] = "-"
+ENV["RUBYOPT"] = "-rpurelib.rb"
 
 MTIMES = [__FILE__, 'rbconfig.rb', srcdir+'/lib/mkmf.rb'].collect {|f| File.mtime(f)}
 
diff --git a/ext/purelib.rb b/ext/purelib.rb
new file mode 100644
index 0000000000..10ee06176c
--- /dev/null
+++ b/ext/purelib.rb
@@ -0,0 +1,3 @@
+if nul = $:.index("-")
+  $:[nul..-1] = ["."]
+end
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 2189a436ee..21fc2fce1f 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -1052,6 +1052,9 @@ topdir = #{($extmk ? CONFIG["topdir"] : $topdir).quote}
 hdrdir = #{$extmk ? CONFIG["hdrdir"].quote : '$(topdir)'}
 VPATH = #{vpath.join(CONFIG['PATH_SEPARATOR'])}
 }
+  if $extmk
+    mk << "RUBYLIB = -\nRUBYOPT = -rpurelib.rb\n"
+  end
   if destdir = CONFIG["prefix"][$dest_prefix_pattern, 1]
     mk << "\nDESTDIR = #{destdir}\n"
   end
diff --git a/runruby.rb b/runruby.rb
index cc04895c33..767ded6b44 100755
--- a/runruby.rb
+++ b/runruby.rb
@@ -41,7 +41,9 @@ config["bindir"] = abs_archdir
 ENV["RUBY"] = File.expand_path(ruby)
 ENV["PATH"] = [abs_archdir, ENV["PATH"]].compact.join(File::PATH_SEPARATOR)
 
-if e = ENV["RUBYLIB"]
+if pure
+  libs << File.expand_path("ext", srcdir) << "-"
+elsif e = ENV["RUBYLIB"]
   libs |= e.split(File::PATH_SEPARATOR)
 end
 ENV["RUBYLIB"] = $:.replace(libs).join(File::PATH_SEPARATOR)
@@ -56,4 +58,8 @@ if File.file?(libruby_so)
   end
 end
 
-exec ruby, *ARGV
+cmd = [ruby]
+cmd << "-rpurelib.rb" if pure
+cmd.concat(ARGV)
+cmd.unshift(*debugger) if debugger
+exec(*cmd)
diff --git a/version.h b/version.h
index 86847162e7..f31cd95719 100644
--- a/version.h
+++ b/version.h
@@ -2,7 +2,7 @@
 #define RUBY_RELEASE_DATE "2007-05-23"
 #define RUBY_VERSION_CODE 186
 #define RUBY_RELEASE_CODE 20070523
-#define RUBY_PATCHLEVEL 24
+#define RUBY_PATCHLEVEL 25
 
 #define RUBY_VERSION_MAJOR 1
 #define RUBY_VERSION_MINOR 8