diff --git a/ChangeLog b/ChangeLog
index b14b9286dd..a1bb258244 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Feb  6 22:25:00 2013  Charlie Somerville  <charlie@charliesomerville.com>
+
+	* hash.c (env_reject_bang): hide keys array from ObjectSpace
+	* hash.c (env_select_bang): ditto
+
 Wed Feb  6 17:33:01 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in (multiarch): add option to move architecture dependent
diff --git a/hash.c b/hash.c
index 48201b6e60..a2261bdf93 100644
--- a/hash.c
+++ b/hash.c
@@ -2713,6 +2713,7 @@ env_reject_bang(VALUE ehash)
 
     RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
     keys = env_keys();	/* rb_secure(4); */
+    RBASIC(keys)->klass = 0;
     for (i=0; i<RARRAY_LEN(keys); i++) {
 	VALUE val = rb_f_getenv(Qnil, RARRAY_PTR(keys)[i]);
 	if (!NIL_P(val)) {
@@ -2816,6 +2817,7 @@ env_select_bang(VALUE ehash)
 
     RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
     keys = env_keys();	/* rb_secure(4); */
+    RBASIC(keys)->klass = 0;
     for (i=0; i<RARRAY_LEN(keys); i++) {
 	VALUE val = rb_f_getenv(Qnil, RARRAY_PTR(keys)[i]);
 	if (!NIL_P(val)) {