diff --git a/mozilla/mail/components/compose/content/messengercompose.xul b/mozilla/mail/components/compose/content/messengercompose.xul
index 8a0d7ef030f..265e216a67f 100644
--- a/mozilla/mail/components/compose/content/messengercompose.xul
+++ b/mozilla/mail/components/compose/content/messengercompose.xul
@@ -660,7 +660,7 @@
   </toolbox>
 
   <hbox flex="1">
-    <vbox id="sidebar-box" persist="sidebarVisible" hidden="true">
+    <vbox id="sidebar-box" persist="sidebarVisible width" hidden="true">
       <sidebarheader align="center">
         <label id="sidebar-title" value="&addressesSidebarTitle.label;"/>
         <spacer flex="1"/>