diff --git a/ChangeLog b/ChangeLog
index ce29d341b2..9370e37a09 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Jun 17 18:15:57 2013  Benoit Daloze  <eregontp@gmail.com>
+
+	* ext/objspace/objspace.c: let rdoc know about objspace methods.
+	  Specify 'objspace' should be required. See #8537.
+
 Mon Jun 17 17:44:31 2013  Benoit Daloze  <eregontp@gmail.com>
 
 	* gc.c (ObjectSpace): is a module not a class.
diff --git a/ext/objspace/objspace.c b/ext/objspace/objspace.c
index 0bdd626705..2e51a3a6e5 100644
--- a/ext/objspace/objspace.c
+++ b/ext/objspace/objspace.c
@@ -155,6 +155,7 @@ memsize_of(VALUE obj)
  *  T_DATA may not be correct.
  *
  *  This method is not expected to work except C Ruby.
+ *  You need to <code>require 'objspace'</code> to use this method.
  */
 
 static VALUE
@@ -221,6 +222,7 @@ total_i(void *vstart, void *vend, size_t stride, void *ptr)
  *  end
  *
  *  This method is not expected to work except C Ruby.
+ *  You need to <code>require 'objspace'</code> to use this method.
  */
 
 static VALUE
@@ -317,6 +319,7 @@ type2sym(enum ruby_value_type i)
  *  It may be changed in future.
  *
  *  This method is not expected to work except C Ruby.
+ *  You need to <code>require 'objspace'</code> to use this method.
  */
 
 static VALUE
@@ -392,6 +395,7 @@ cn_i(void *vstart, void *vend, size_t stride, void *n)
  *  It may be changed in future.
  *
  *  This method is not expected to work except C Ruby.
+ *  You need to <code>require 'objspace'</code> to use this method.
  */
 
 static VALUE
@@ -600,7 +604,7 @@ cto_i(void *vstart, void *vend, size_t stride, void *data)
  *  name, registered by rb_data_type_struct.
  *
  *  This method is not expected to work except C Ruby.
- *
+ *  You need to <code>require 'objspace'</code> to use this method.
  */
 
 static VALUE
@@ -728,6 +732,7 @@ collect_values(st_data_t key, st_data_t value, st_data_t data)
  *  With this method, you can find memory leaks.
  *
  *  This method is not expected to work except in C Ruby.
+ *  You need to <code>require 'objspace'</code> to use this method.
  *
  *  Example:
  *    ObjectSpace.reachable_objects_from(['a', 'b', 'c'])
@@ -789,7 +794,11 @@ void Init_gc_hook(VALUE rb_mObjSpace);
 void
 Init_objspace(void)
 {
-    VALUE rb_mObjSpace = rb_const_get(rb_cObject, rb_intern("ObjectSpace"));
+    VALUE rb_mObjSpace;
+#if 0
+    rb_mObjSpace = rb_define_module("ObjectSpace"); /* let rdoc know */
+#endif
+    rb_mObjSpace = rb_const_get(rb_cObject, rb_intern("ObjectSpace"));
 
     rb_define_module_function(rb_mObjSpace, "memsize_of", memsize_of_m, 1);
     rb_define_module_function(rb_mObjSpace, "memsize_of_all", memsize_of_all_m, -1);