diff --git a/tests/wpt/mozilla/tests/mozilla/characterdata.html b/tests/wpt/mozilla/tests/mozilla/characterdata.html
index 22b7aa3c65d..9e8bb9fd10e 100644
--- a/tests/wpt/mozilla/tests/mozilla/characterdata.html
+++ b/tests/wpt/mozilla/tests/mozilla/characterdata.html
@@ -9,14 +9,7 @@
   <script>
   test(function() {
     var a = document.getElementsByTagName('p')[0].childNodes[0];
-    a.data = "This is the character data test, append more 資料，更多測試資料";
-
-    // delete test non-utf8
-    a.deleteData(40, 5);
-    assert_equals(a.data, "This is the character data test, append 資料，更多測試資料");
-    // delete test utf8
-    a.deleteData(45, 2);
-    assert_equals(a.data, "This is the character data test, append 資料，更多資料");
+    a.data = "This is the character data test, append 資料，更多資料";
 
     // replace test non-utf8
     a.replaceData(33, 6, "other");
diff --git a/tests/wpt/web-platform-tests/dom/nodes/CharacterData-deleteData.html b/tests/wpt/web-platform-tests/dom/nodes/CharacterData-deleteData.html
index 5715e0b1de7..9ea85ee33ee 100644
--- a/tests/wpt/web-platform-tests/dom/nodes/CharacterData-deleteData.html
+++ b/tests/wpt/web-platform-tests/dom/nodes/CharacterData-deleteData.html
@@ -31,6 +31,16 @@ function testNode(create, type) {
     node.deleteData(1, 1)
     assert_equals(node.data, "tst")
   }, type + ".deleteData() in the middle")
+
+  test(function() {
+    var node = create()
+    node.data = "This is the character data test, append more 資料，更多測試資料";
+
+    node.deleteData(40, 5);
+    assert_equals(node.data, "This is the character data test, append 資料，更多測試資料");
+    node.deleteData(45, 2);
+    assert_equals(node.data, "This is the character data test, append 資料，更多資料");
+  }, type + ".deleteData() with non-ascii data")
 }
 
 testNode(function() { return document.createTextNode("test") }, "Text")