diff --git a/mozilla/docshell/base/nsWebShell.cpp b/mozilla/docshell/base/nsWebShell.cpp
index 7795f9b18c9..6e9b9d569d2 100644
--- a/mozilla/docshell/base/nsWebShell.cpp
+++ b/mozilla/docshell/base/nsWebShell.cpp
@@ -808,16 +808,39 @@ nsWebShell::Embed(nsIContentViewer* aContentViewer,
       ("nsWebShell::Embed: this=%p aDocViewer=%p aCommand=%s aExtraInfo=%p",
        this, aContentViewer, aCommand ? aCommand : "", aExtraInfo));
 
+  //
+  // The following logic is mirrored in nsHTMLDocument::StartDocumentLoad!
+  //
+  nsCOMPtr<nsIMarkupDocumentViewer> oldMUDV;
   if (mContentViewer) // && (eCharsetReloadInit!=mCharsetReloadState))
   { // get any interesting state from the old content viewer
     // XXX: it would be far better to just reuse the document viewer ,
     //      since we know we're just displaying the same document as before
+    oldMUDV = do_QueryInterface(mContentViewer);
+  }
+  else
+  { // If we don't have an old content viewer, get state from our parent
+    // in this block of code, if we get an error result, we return it
+    // but if we get a null pointer, that's perfectly legal for parent and parentContentViewer
+    nsCOMPtr<nsIWebShell> parent;
+    rv = GetParent(*getter_AddRefs(parent));
+    if (NS_FAILED(rv)) { return rv; }
+    if (parent) {
+      nsCOMPtr<nsIContentViewer> parentContentViewer;
+      rv = parent->GetContentViewer(getter_AddRefs(parentContentViewer));
+      if (NS_FAILED(rv)) { return rv; }
+      if (parentContentViewer) {
+        oldMUDV = do_QueryInterface(parentContentViewer);
+      }
+    }
+  }
+
+  if (oldMUDV) {
     PRUnichar *defaultCharset=nsnull;
     PRUnichar *forceCharset=nsnull;
     PRUnichar *hintCharset=nsnull;
     PRInt32 hintCharsetSource;
 
-    nsCOMPtr<nsIMarkupDocumentViewer> oldMUDV = do_QueryInterface(mContentViewer);
     nsCOMPtr<nsIMarkupDocumentViewer> newMUDV = do_QueryInterface(aContentViewer);
     if (oldMUDV && newMUDV)
     {
diff --git a/mozilla/webshell/src/nsWebShell.cpp b/mozilla/webshell/src/nsWebShell.cpp
index 7795f9b18c9..6e9b9d569d2 100644
--- a/mozilla/webshell/src/nsWebShell.cpp
+++ b/mozilla/webshell/src/nsWebShell.cpp
@@ -808,16 +808,39 @@ nsWebShell::Embed(nsIContentViewer* aContentViewer,
       ("nsWebShell::Embed: this=%p aDocViewer=%p aCommand=%s aExtraInfo=%p",
        this, aContentViewer, aCommand ? aCommand : "", aExtraInfo));
 
+  //
+  // The following logic is mirrored in nsHTMLDocument::StartDocumentLoad!
+  //
+  nsCOMPtr<nsIMarkupDocumentViewer> oldMUDV;
   if (mContentViewer) // && (eCharsetReloadInit!=mCharsetReloadState))
   { // get any interesting state from the old content viewer
     // XXX: it would be far better to just reuse the document viewer ,
     //      since we know we're just displaying the same document as before
+    oldMUDV = do_QueryInterface(mContentViewer);
+  }
+  else
+  { // If we don't have an old content viewer, get state from our parent
+    // in this block of code, if we get an error result, we return it
+    // but if we get a null pointer, that's perfectly legal for parent and parentContentViewer
+    nsCOMPtr<nsIWebShell> parent;
+    rv = GetParent(*getter_AddRefs(parent));
+    if (NS_FAILED(rv)) { return rv; }
+    if (parent) {
+      nsCOMPtr<nsIContentViewer> parentContentViewer;
+      rv = parent->GetContentViewer(getter_AddRefs(parentContentViewer));
+      if (NS_FAILED(rv)) { return rv; }
+      if (parentContentViewer) {
+        oldMUDV = do_QueryInterface(parentContentViewer);
+      }
+    }
+  }
+
+  if (oldMUDV) {
     PRUnichar *defaultCharset=nsnull;
     PRUnichar *forceCharset=nsnull;
     PRUnichar *hintCharset=nsnull;
     PRInt32 hintCharsetSource;
 
-    nsCOMPtr<nsIMarkupDocumentViewer> oldMUDV = do_QueryInterface(mContentViewer);
     nsCOMPtr<nsIMarkupDocumentViewer> newMUDV = do_QueryInterface(aContentViewer);
     if (oldMUDV && newMUDV)
     {