diff --git a/mozilla/editor/base/nsComposerController.cpp b/mozilla/editor/base/nsComposerController.cpp
index c51d02b64d6..5d0381ec7f6 100644
--- a/mozilla/editor/base/nsComposerController.cpp
+++ b/mozilla/editor/base/nsComposerController.cpp
@@ -162,6 +162,7 @@ nsresult nsComposerController::RegisterComposerCommands(nsIControllerCommandMana
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_bold", "b");
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_italic", "i");
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_underline", "u");
+  NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_tt", "tt");
 
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_strikethrough", "strike");
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_superscript", "sup");
diff --git a/mozilla/editor/composer/src/nsComposerController.cpp b/mozilla/editor/composer/src/nsComposerController.cpp
index c51d02b64d6..5d0381ec7f6 100644
--- a/mozilla/editor/composer/src/nsComposerController.cpp
+++ b/mozilla/editor/composer/src/nsComposerController.cpp
@@ -162,6 +162,7 @@ nsresult nsComposerController::RegisterComposerCommands(nsIControllerCommandMana
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_bold", "b");
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_italic", "i");
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_underline", "u");
+  NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_tt", "tt");
 
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_strikethrough", "strike");
   NS_REGISTER_STYLE_COMMAND(nsStyleUpdatingCommand, "cmd_superscript", "sup");