diff --git a/mozilla/content/base/test/test_bug431701.html b/mozilla/content/base/test/test_bug431701.html
index fc757b302e1..258ae211c64 100644
--- a/mozilla/content/base/test/test_bug431701.html
+++ b/mozilla/content/base/test/test_bug431701.html
@@ -71,7 +71,7 @@ var tests = [
  [ frameDoc("five"), "UTF-8", "UTF-8", null ],
  [ frameDoc("six"), "UTF-8", "UTF-8", "UTF-8"],
  [ frameDoc("seven"), "ISO-8859-1", "ISO-8859-1", "ISO-8859-1" ],
- [ createDoc, "ISO-8859-1", null, null ],
+ [ createDoc, "UTF-8", null, null ],
  [ xhrDoc(4), "UTF-8", "UTF-8", null ],
  [ xhrDoc(5), "UTF-8", "UTF-8", "UTF-8" ],
  [ xhrDoc(6), "ISO-8859-1", "ISO-8859-1", "ISO-8859-1" ],
diff --git a/mozilla/content/xml/document/src/nsXMLDocument.cpp b/mozilla/content/xml/document/src/nsXMLDocument.cpp
index e1a29c5391f..d894b192109 100644
--- a/mozilla/content/xml/document/src/nsXMLDocument.cpp
+++ b/mozilla/content/xml/document/src/nsXMLDocument.cpp
@@ -133,6 +133,10 @@ NS_NewDOMDocument(nsIDOMDocument** aInstancePtrResult,
   doc->SetPrincipal(aPrincipal);
   doc->SetBaseURI(aBaseURI);
 
+  // XMLDocuments and documents "created in memory" get to be UTF-8 by default,
+  // unlike the legacy HTML mess
+  doc->SetDocumentCharacterSet(NS_LITERAL_CSTRING("UTF-8"));
+  
   if (aDoctype) {
     nsCOMPtr<nsIDOMNode> tmpNode;
     rv = doc->AppendChild(aDoctype, getter_AddRefs(tmpNode));