diff --git a/ChangeLog b/ChangeLog
index d35ada9a27..86f9dde8cb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Oct 30 12:08:41 2013  Masaki Matsushita  <glass.saga@gmail.com>
+
+	* array.c (rb_ary_uniq_bang): use rb_ary_modify_check() instead of
+	  rb_ary_modify() because the array will be unshared soon.
+
 Wed Oct 30 03:25:10 2013  Aaron Patterson <aaron@tenderlovemaking.com>
 
 	* ext/psych/lib/psych/visitors/yaml_tree.rb: make less garbage when
diff --git a/array.c b/array.c
index 5e122a22f9..c7428c5b21 100644
--- a/array.c
+++ b/array.c
@@ -4111,7 +4111,7 @@ rb_ary_uniq_bang(VALUE ary)
 	if (RARRAY_LEN(ary) == hash_size) {
 	    return Qnil;
 	}
-	rb_ary_modify(ary);
+	rb_ary_modify_check(ary);
 	ARY_SET_LEN(ary, 0);
 	if (ARY_SHARED_P(ary) && !ARY_EMBED_P(ary)) {
 	    rb_ary_unshare(ary);
@@ -4126,7 +4126,7 @@ rb_ary_uniq_bang(VALUE ary)
 	if (RARRAY_LEN(ary) == hash_size) {
 	    return Qnil;
 	}
-	rb_ary_modify(ary);
+	rb_ary_modify_check(ary);
 	ARY_SET_LEN(ary, 0);
 	if (ARY_SHARED_P(ary) && !ARY_EMBED_P(ary)) {
 	    rb_ary_unshare(ary);