diff --git a/toolkit/components/help/content/help.xul b/toolkit/components/help/content/help.xul
index 8d70353d40b..fb84b30065b 100644
--- a/toolkit/components/help/content/help.xul
+++ b/toolkit/components/help/content/help.xul
@@ -112,6 +112,8 @@
             command="cmd_textZoomEnlarge" modifiers="accel"/>
         <key id="key_textZoomReduce" key="&textZoomReduceCmd.commandkey;"
             command="cmd_textZoomReduce" modifiers="accel"/>
+        <key id="key_textZoomReset" key="&textZoomResetCmd.commandkey;"
+            oncommand="ZoomManager.prototype.getInstance().reset();" modifiers="accel"/>
         <key id="key_toggleSidebar" keycode="VK_F9" command="Help:ToggleSidebar"/>
         <key id="key_viewNextHelpPanel" keycode="VK_TAB" 
              oncommand="showRelativePanel(true);" modifiers="control"/>
diff --git a/toolkit/components/help/locale/en-US/help.dtd b/toolkit/components/help/locale/en-US/help.dtd
index 910eef5c3c5..4c05baae2a0 100644
--- a/toolkit/components/help/locale/en-US/help.dtd
+++ b/toolkit/components/help/locale/en-US/help.dtd
@@ -52,3 +52,4 @@
 <!ENTITY textZoomReduceCmd.commandkey	"-">
 <!ENTITY textZoomEnlargeCmd.commandkey	"+">
 <!ENTITY textZoomEnlargeCmd.commandkey2 "="> <!-- + is above this key on many keyboards -->
+<!ENTITY textZoomResetCmd.commandkey    "0">