diff --git a/ChangeLog b/ChangeLog
index 221e6f9d37..d0fd0dc0ac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Wed Jun 12 16:41:38 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* array.c (rb_ary_sort_bang): remove duplicated assertions.
+	  ARY_HEAP_PTR() implies ary not to be embedded.  [ruby-dev:47419]
+	  [Bug #8518]
+
 Wed Jun 12 12:44:45 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* io.c (io_getc): fix 7bit coderange condition, check if ascii read
diff --git a/array.c b/array.c
index f3076d7cf3..da22b4c841 100644
--- a/array.c
+++ b/array.c
@@ -2323,7 +2323,6 @@ rb_ary_sort_bang(VALUE ary)
 
 	rb_ary_modify(ary);
         if (ARY_EMBED_P(tmp)) {
-            assert(ARY_EMBED_P(tmp));
             if (ARY_SHARED_P(ary)) { /* ary might be destructively operated in the given block */
                 rb_ary_unshare(ary);
             }
@@ -2332,9 +2331,7 @@ rb_ary_sort_bang(VALUE ary)
             ARY_SET_LEN(ary, ARY_EMBED_LEN(tmp));
         }
         else {
-            assert(!ARY_EMBED_P(tmp));
-            if (ARY_HEAP_PTR(ary) == ARY_HEAP_PTR(tmp)) {
-                assert(!ARY_EMBED_P(ary));
+            if (!ARY_EMBED_P(ary) && ARY_HEAP_PTR(ary) == ARY_HEAP_PTR(tmp)) {
                 FL_UNSET_SHARED(ary);
                 ARY_SET_CAPA(ary, RARRAY_LEN(tmp));
             }