diff --git a/bootstraptest/test_knownbug.rb b/bootstraptest/test_knownbug.rb
index b251734cae..c0cd0e9f31 100644
--- a/bootstraptest/test_knownbug.rb
+++ b/bootstraptest/test_knownbug.rb
@@ -10,3 +10,19 @@ assert_equal 'ok', %q{
   }
   s == "a\xFF" ? :ok : :ng
 }, '[ruby-core:14288]'
+
+assert_equal 'ok', %q{
+  open("require-lock-test.rb", "w") {|f|
+    f.puts "sleep 0.1"
+    f.puts "module M"
+    f.puts "end"
+  }
+  $:.unshift Dir.pwd
+  vs = (1..2).map {|i|
+    Thread.start {
+      require "require-lock-test"
+      M
+    }
+  }.map {|t| t.value }
+  vs[0] == M && vs[1] == M ? :ok : :ng
+}, '[ruby-dev:32048]'