diff --git a/ChangeLog b/ChangeLog
index 67eb03be25..f22e9f086a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Wed Nov 27 15:55:52 2013  Aman Gupta <ruby@tmm1.net>
+
+	* gc.c (Init_GC): Add new GC::INTERNAL_CONSTANTS for information about
+	  GC heap/page/slot sizing.
+	* test/ruby/test_gc.rb (class TestGc): test for above.
+
 Wed Nov 27 15:21:17 2013  Aman Gupta <ruby@tmm1.net>
 
 	* gc.c (gc_page_sweep): Fix compile warning from last commit.
diff --git a/gc.c b/gc.c
index 12ef935849..0adf549334 100644
--- a/gc.c
+++ b/gc.c
@@ -6984,6 +6984,7 @@ Init_GC(void)
 {
     VALUE rb_mObjSpace;
     VALUE rb_mProfiler;
+    VALUE gc_constants;
 
     rb_mGC = rb_define_module("GC");
     rb_define_singleton_method(rb_mGC, "start", rb_gc_start, 0);
@@ -6995,6 +6996,14 @@ Init_GC(void)
     rb_define_singleton_method(rb_mGC, "stat", gc_stat, -1);
     rb_define_method(rb_mGC, "garbage_collect", rb_gc_start, 0);
 
+    gc_constants = rb_hash_new();
+    rb_hash_aset(gc_constants, ID2SYM(rb_intern("RVALUE_SIZE")), SIZET2NUM(sizeof(RVALUE)));
+    rb_hash_aset(gc_constants, ID2SYM(rb_intern("HEAP_OBJ_LIMIT")), SIZET2NUM(HEAP_OBJ_LIMIT));
+    rb_hash_aset(gc_constants, ID2SYM(rb_intern("HEAP_BITMAP_SIZE")), SIZET2NUM(HEAP_BITMAP_SIZE));
+    rb_hash_aset(gc_constants, ID2SYM(rb_intern("HEAP_BITMAP_PLANES")), SIZET2NUM(HEAP_BITMAP_PLANES));
+    OBJ_FREEZE(gc_constants);
+    rb_define_const(rb_mGC, "INTERNAL_CONSTANTS", gc_constants);
+
     rb_mProfiler = rb_define_module_under(rb_mGC, "Profiler");
     rb_define_singleton_method(rb_mProfiler, "enabled?", gc_profile_enable_get, 0);
     rb_define_singleton_method(rb_mProfiler, "enable", gc_profile_enable, 0);
diff --git a/test/ruby/test_gc.rb b/test/ruby/test_gc.rb
index da4a0b585d..ce7c5c3927 100644
--- a/test/ruby/test_gc.rb
+++ b/test/ruby/test_gc.rb
@@ -212,4 +212,9 @@ class TestGc < Test::Unit::TestCase
     assert base_length < GC.stat[:heap_eden_page_length]
     eom
   end
+
+  def test_gc_internals
+    assert_not_nil GC::INTERNAL_CONSTANTS[:HEAP_OBJ_LIMIT]
+    assert_not_nil GC::INTERNAL_CONSTANTS[:RVALUE_SIZE]
+  end
 end