diff --git a/ChangeLog b/ChangeLog
index 9a737468f8..cac4186fb3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu May  8 16:41:20 2008  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in (MINIRUBY), common.mk (RUBYOPT): add purelib.rb.
+	  [ruby-core:16642]
+
 Thu May  8 16:00:41 2008  Yukihiro Matsumoto  <matz@ruby-lang.org>
 
 	* parse.y (parser_yylex): ! and ? at the bottom are no longer part
diff --git a/Makefile.in b/Makefile.in
index 9fc2803f5a..038f324447 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -39,6 +39,9 @@ empty =
 OUTFLAG = @OUTFLAG@$(empty)
 COUTFLAG = @COUTFLAG@$(empty)
 CFLAGS = @CFLAGS@ @ARCH_FLAG@
+cflags = @cflags@
+optflags = @optflags@
+debugflags = @debugflags@
 XCFLAGS = -I. -I$(arch_hdrdir) -I$(hdrdir) -I$(srcdir) @XCFLAGS@
 CPPFLAGS = @CPPFLAGS@
 LDFLAGS = @STATIC@ $(CFLAGS) @LDFLAGS@
diff --git a/common.mk b/common.mk
index 6034547f5a..b80d829001 100644
--- a/common.mk
+++ b/common.mk
@@ -4,7 +4,8 @@ dll: $(LIBRUBY_SO)
 
 .SUFFIXES: .inc
 
-RUBYOPT       =
+RUBYLIB       = -
+RUBYOPT       = -rpurelib.rb
 
 STATIC_RUBY   = static-ruby
 
@@ -114,6 +115,9 @@ all: $(MKFILES) $(PREP) incs $(RBCONFIG) $(LIBRUBY) encs
 	@$(MINIRUBY) $(srcdir)/ext/extmk.rb --make="$(MAKE)" $(EXTMK_ARGS)
 prog: $(PROGRAM) $(WPROGRAM)
 
+loadpath: $(PREP)
+	$(MINIRUBY) -e 'p $$:'
+
 $(PREP): $(MKFILES)
 
 miniruby$(EXEEXT): config.status $(NORMALMAINOBJ) $(MINIOBJS) $(COMMONOBJS) $(DMYEXT) $(ARCHFILE)
diff --git a/configure.in b/configure.in
index aeb8ddf6fb..2c51d35ea4 100644
--- a/configure.in
+++ b/configure.in
@@ -1488,6 +1488,8 @@ if test x"$cross_compiling" = xyes; then
   RUNRUBY='$(MINIRUBY) -I`cd $(srcdir)/lib; pwd`'
 else
   MINIRUBY='./miniruby$(EXEEXT) -I$(srcdir)/lib'
+  MINIRUBY="$MINIRUBY"' -I$(EXTOUT)/$(arch) -I$(EXTOUT)/common'
+  MINIRUBY="$MINIRUBY"' -I./- -I$(srcdir)/ext -rpurelib.rb'
   PREP='miniruby$(EXEEXT)'
   RUNRUBY='$(MINIRUBY) $(srcdir)/runruby.rb --extout=$(EXTOUT)'
 fi
diff --git a/ext/extmk.rb b/ext/extmk.rb
index 667aad0573..db2682ef9e 100644
--- a/ext/extmk.rb
+++ b/ext/extmk.rb
@@ -348,7 +348,7 @@ $ruby << " -I'$(topdir)'"
 unless CROSS_COMPILING
   $ruby << " -I'$(top_srcdir)/lib'"
   $ruby << " -I'$(extout)/$(arch)' -I'$(extout)/common'" if $extout
-  $ruby << " -I'$(top_srcdir)/ext' -rpurelib.rb"
+  $ruby << " -I./- -I'$(top_srcdir)/ext' -rpurelib.rb"
   ENV["RUBYLIB"] = "-"
   ENV["RUBYOPT"] = "-rpurelib.rb"
 end
diff --git a/ext/purelib.rb b/ext/purelib.rb
index 10ee06176c..284254a8b4 100644
--- a/ext/purelib.rb
+++ b/ext/purelib.rb
@@ -1,3 +1,3 @@
-if nul = $:.index("-")
+if nul = $:.find_index {|path| /\A(?:\.\/)*-\z/ =~ path}
   $:[nul..-1] = ["."]
 end