diff --git a/tests/content/test_document_characterSet.html b/tests/content/test_document_characterSet.html
index 4ac3dea31be..4e150c682e8 100644
--- a/tests/content/test_document_characterSet.html
+++ b/tests/content/test_document_characterSet.html
@@ -6,13 +6,13 @@
         <script>
             // test1: characterSet
             {
-                is(document.characterSet, "utf-8", "test1-0, characterSet");
+                is(document.characterSet, "UTF-8", "test1-0, characterSet");
 
                 var xmldoc = new Document;
-                is(xmldoc.characterSet, "utf-8", "test2-1, characterSet");
+                is(xmldoc.characterSet, "UTF-8", "test2-1, characterSet");
 
                 var htmldoc = document.implementation.createHTMLDocument("title");
-                is(htmldoc.characterSet, "utf-8", "test2-2, characterSet");
+                is(htmldoc.characterSet, "UTF-8", "test2-2, characterSet");
             }
         </script>
     </head>
diff --git a/tests/content/test_document_characterSet_default.html b/tests/content/test_document_characterSet_default.html
index 1941e50c3ee..2c234636519 100644
--- a/tests/content/test_document_characterSet_default.html
+++ b/tests/content/test_document_characterSet_default.html
@@ -6,7 +6,7 @@
             // test1: default characterSet
             {
                 // FIXME: https://github.com/mozilla-servo/libhubbub/issues/5
-                is(document.characterSet, "utf-8", "test1-0, default characterSet");
+                is(document.characterSet, "UTF-8", "test1-0, default characterSet");
             }
         </script>
     </head>
diff --git a/tests/content/test_document_characterSet_invalid.html b/tests/content/test_document_characterSet_invalid.html
index d0440e4fe0f..15ab99519c2 100644
--- a/tests/content/test_document_characterSet_invalid.html
+++ b/tests/content/test_document_characterSet_invalid.html
@@ -6,7 +6,7 @@
         <script>
             // test1: unknown charset
             {
-                is(document.characterSet, "utf-8", "test1-0, unknown charset");
+                is(document.characterSet, "UTF-8", "test1-0, unknown charset");
             }
         </script>
     </head>