diff --git a/ChangeLog b/ChangeLog
index 9c3991be20..4bbee66e61 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Tue Jun 11 16:15:03 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* array.c (ary_shrink_capa): shrink the capacity so it fits just with
+	  the length.
+
+	* array.c (ary_make_shared): release never used elements from frozen
+	  array to be shared.  [ruby-dev:47416] [Bug #8510]
+
 Tue Jun 11 12:49:01 2013  Zachary Scott  <zachary@zacharyscott.net>
 
 	* doc/re.rdoc: Rename to doc/regexp.rdoc
diff --git a/array.c b/array.c
index 8ef0b860ee..eed646bd5f 100644
--- a/array.c
+++ b/array.c
@@ -179,6 +179,16 @@ ary_resize_capa(VALUE ary, long capacity)
     }
 }
 
+static void
+ary_shrink_capa(VALUE ary)
+{
+    long capacity = ARY_HEAP_LEN(ary);
+    long old_capa = RARRAY(ary)->as.heap.aux.capa;
+    assert(old_capa >= capacity);
+    if (old_capa > capacity)
+	REALLOC_N(RARRAY(ary)->as.heap.ptr, VALUE, capacity);
+}
+
 static void
 ary_double_capa(VALUE ary, long min)
 {
@@ -510,7 +520,7 @@ ary_make_shared(VALUE ary)
 	return ary;
     }
     else if (OBJ_FROZEN(ary)) {
-	ary_resize_capa(ary, ARY_HEAP_LEN(ary));
+	ary_shrink_capa(ary);
 	FL_SET_SHARED_ROOT(ary);
 	ARY_SET_SHARED_NUM(ary, 1);
 	return ary;