diff --git a/mozilla/content/html/document/src/nsHTMLDocument.cpp b/mozilla/content/html/document/src/nsHTMLDocument.cpp
index 9a347fed32e..16d6b93b54b 100644
--- a/mozilla/content/html/document/src/nsHTMLDocument.cpp
+++ b/mozilla/content/html/document/src/nsHTMLDocument.cpp
@@ -4184,7 +4184,7 @@ static struct MidasCommand gMidasCommandTable[] = {
   { "increasefontsize", "cmd_increaseFont", "", PR_FALSE },
   { "decreasefontsize", "cmd_decreaseFont", "", PR_FALSE },
   { "fontsize",      "cmd_fontSize",        "", PR_FALSE },
-  { "inserthorizontalrule", "cmd_hline",    "", PR_TRUE },
+  { "inserthorizontalrule", "cmd_insertHR", "", PR_TRUE },
   { "createlink",    "cmd_insertLinkNoUI",  "", PR_FALSE },
   { "insertimage",   "cmd_insertImageNoUI", "", PR_FALSE },
   { "justifyleft",   "cmd_align",       "left", PR_TRUE },
diff --git a/mozilla/editor/composer/src/nsComposerCommands.cpp b/mozilla/editor/composer/src/nsComposerCommands.cpp
index 53679fda5e5..c95587bdc00 100644
--- a/mozilla/editor/composer/src/nsComposerCommands.cpp
+++ b/mozilla/editor/composer/src/nsComposerCommands.cpp
@@ -1315,6 +1315,22 @@ nsInsertTagCommand::IsCommandEnabled(const char * aCommandName,
 NS_IMETHODIMP
 nsInsertTagCommand::DoCommand(const char *aCmdName, nsISupports *refCon)
 {
+  if (0 == nsCRT::strcmp(mTagName, "hr"))
+  {
+    nsCOMPtr<nsIHTMLEditor> editor = do_QueryInterface(refCon);
+    if (!editor)
+      return NS_ERROR_NOT_IMPLEMENTED;
+
+    nsCOMPtr<nsIDOMElement> domElem;
+    nsresult rv;
+    rv = editor->CreateElementWithDefaults(NS_ConvertASCIItoUCS2(mTagName),
+                                           getter_AddRefs(domElem));
+    if (NS_FAILED(rv))
+      return rv;
+
+    return editor->InsertElementAtSelection(domElem, PR_TRUE);
+  }
+
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
@@ -1323,9 +1339,14 @@ nsInsertTagCommand::DoCommandParams(const char *aCommandName,
                                     nsICommandParams *aParams,
                                     nsISupports *refCon)
 {
-  NS_ENSURE_ARG_POINTER(aParams);
   NS_ENSURE_ARG_POINTER(refCon);
 
+  // inserting an hr shouldn't have an parameters, just call DoCommand for that
+  if (0 == nsCRT::strcmp(mTagName, "hr"))
+    return DoCommand(aCommandName, refCon);
+
+  NS_ENSURE_ARG_POINTER(aParams);
+
   nsCOMPtr<nsIHTMLEditor> editor = do_QueryInterface(refCon);
   if (!editor)
     return NS_ERROR_NOT_IMPLEMENTED;
diff --git a/mozilla/editor/composer/src/nsComposerController.cpp b/mozilla/editor/composer/src/nsComposerController.cpp
index de9311239ab..1317ab2a531 100644
--- a/mozilla/editor/composer/src/nsComposerController.cpp
+++ b/mozilla/editor/composer/src/nsComposerController.cpp
@@ -163,6 +163,7 @@ nsComposerController::RegisterHTMLEditorCommands(
   NS_REGISTER_ONE_COMMAND(nsInsertHTMLCommand, "cmd_insertHTML");
   NS_REGISTER_TAG_COMMAND(nsInsertTagCommand, "cmd_insertLinkNoUI", "a");
   NS_REGISTER_TAG_COMMAND(nsInsertTagCommand, "cmd_insertImageNoUI", "img");
+  NS_REGISTER_TAG_COMMAND(nsInsertTagCommand, "cmd_insertHR", "hr");
 
   return NS_OK;
 }