diff --git a/ChangeLog b/ChangeLog
index 46f8d613b0..6dd7a06b27 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Jul  9 08:39:39 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* common.mk (RUN_OPT): disable gems.
+
 Sat Jul  9 08:37:05 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* io.c (rb_io_close): close(2) on a fd which is being read by
diff --git a/Makefile.in b/Makefile.in
index 531743d0e8..b1864e68e3 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -80,7 +80,7 @@ PROGRAM=$(RUBY_INSTALL_NAME)$(EXEEXT)
 RUBY = $(RUBY_INSTALL_NAME)
 MINIRUBY = @MINIRUBY@\
 	$(MINIRUBYOPT)
-RUNRUBY = @RUNRUBY@ $(RUNRUBYOPT) --
+RUNRUBY = @RUNRUBY@ $(RUNRUBYOPT) -- $(RUN_OPTS)
 XRUBY = @XRUBY@
 INSTALL = @INSTALL@
 INSTALL_DATA = @INSTALL_DATA@
diff --git a/common.mk b/common.mk
index e9a93b1dd3..573b64a662 100644
--- a/common.mk
+++ b/common.mk
@@ -13,6 +13,7 @@ ECHO = $(ECHO1:0=@echo)
 
 RUBYLIB       = -
 RUBYOPT       = -
+RUN_OPTS      = --disable-gems
 
 SPEC_GIT_BASE = git://github.com/rubyspec
 MSPEC_GIT_URL = $(SPEC_GIT_BASE)/mspec.git
diff --git a/test/runner.rb b/test/runner.rb
index 608af08922..72b2360cd8 100644
--- a/test/runner.rb
+++ b/test/runner.rb
@@ -4,6 +4,8 @@ require 'test/unit'
 
 src_testdir = File.dirname(File.expand_path(__FILE__))
 $LOAD_PATH << src_testdir
+module Gem
+end
 class Gem::TestCase < MiniTest::Unit::TestCase
   @@project_dir = File.dirname($LOAD_PATH.last)
 end
diff --git a/win32/Makefile.sub b/win32/Makefile.sub
index 46c1bc7dcf..808966a4e0 100644
--- a/win32/Makefile.sub
+++ b/win32/Makefile.sub
@@ -270,7 +270,7 @@ MINIRUBY = .\miniruby$(EXEEXT) -I$(srcdir)/lib -I.
 RUNRUBY = .\$(PROGRAM) -I$(srcdir)/lib -I"$(EXTOUT)/$(arch)" -I.
 !endif
 MINIRUBY = $(MINIRUBY) $(MINIRUBYOPT)
-RUNRUBY = $(RUNRUBY) "$(srcdir)/tool/runruby.rb" --extout="$(EXTOUT)" $(RUNRUBYOPT) --
+RUNRUBY = $(RUNRUBY) "$(srcdir)/tool/runruby.rb" --extout="$(EXTOUT)" $(RUNRUBYOPT) -- $(RUN_OPTS)
 !if $(CROSS_COMPILING)
 XRUBY = $(MINIRUBY)
 !else