diff --git a/ChangeLog b/ChangeLog
index 356a6e0a40..41a8cbaa71 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Oct  1 15:17:48 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* gc.c (id2ref): T_VALUES is less than T_BLOCK.  [ruby-dev:31911]
+
 Mon Oct  1 10:58:42 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ruby.c (require_libraries): use require method instead of calling
diff --git a/bootstraptest/test_knownbug.rb b/bootstraptest/test_knownbug.rb
index f75a714590..5ac0cd11fd 100644
--- a/bootstraptest/test_knownbug.rb
+++ b/bootstraptest/test_knownbug.rb
@@ -33,20 +33,6 @@ assert_normal_exit %q{
   Marshal.load(Marshal.dump({"k"=>"v"}), lambda {|v| })
 }
 
-assert_normal_exit %q{
-  eval("", TOPLEVEL_BINDING)
-  minobj = ObjectSpace.to_enum(:each_object).min {|a,b| a.object_id <=> b.object_id }
-  maxobj = ObjectSpace.to_enum(:each_object).max {|a,b| a.object_id <=> b.object_id }
-  minobj.object_id.upto(maxobj.object_id) {|id|
-    begin
-      o = ObjectSpace._id2ref(id)
-    rescue RangeError
-      next
-    end
-    o.inspect
-  }
-}, '[ruby-dev:31911]'
-
 assert_normal_exit %q{
   require 'continuation'
   Fiber.new{ callcc{|c| @c = c } }.resume
diff --git a/bootstraptest/test_objectspace.rb b/bootstraptest/test_objectspace.rb
new file mode 100644
index 0000000000..f138ac5f6c
--- /dev/null
+++ b/bootstraptest/test_objectspace.rb
@@ -0,0 +1,13 @@
+assert_normal_exit %q{
+  eval("", TOPLEVEL_BINDING)
+  minobj = ObjectSpace.to_enum(:each_object).min_by {|a| a.object_id }
+  maxobj = ObjectSpace.to_enum(:each_object).max_by {|a| a.object_id }
+  minobj.object_id.upto(maxobj.object_id) {|id|
+    begin
+      o = ObjectSpace._id2ref(id)
+    rescue RangeError
+      next
+    end
+    o.inspect if defined?(o.inspect)
+  }
+}, '[ruby-dev:31911]'
diff --git a/gc.c b/gc.c
index 7dd5c4e681..4b239b634a 100644
--- a/gc.c
+++ b/gc.c
@@ -2069,7 +2069,7 @@ id2ref(VALUE obj, VALUE objid)
 	return ID2SYM(symid);
     }
 
-    if (!is_pointer_to_heap((void *)ptr)|| BUILTIN_TYPE(ptr) >= T_BLOCK) {
+    if (!is_pointer_to_heap((void *)ptr) || BUILTIN_TYPE(ptr) >= T_VALUES) {
 	rb_raise(rb_eRangeError, "%p is not id value", p0);
     }
     if (BUILTIN_TYPE(ptr) == 0 || RBASIC(ptr)->klass == 0) {