--- a/mail/components/preferences/compose.xul
+++ b/mail/components/preferences/compose.xul
@@ -216,17 +216,18 @@
                         preference="mail.collect_addressbook"
                         aria-labelledby="emailCollectionOutgoing">
                 <menupopup id="abPopup-menupopup" class="addrbooksPopup"
                            localonly="true" writable="true"/>
               </menulist>
             </hbox>
 
            <hbox align="center" pack="start">
-             <label value="&showAsDefault.label;" accesskey="&showAsDefault.accesskey;"/>
+             <label value="&showAsDefault.label;" accesskey="&showAsDefault.accesskey;"
+                    control="defaultStartupDirList"/>
              <menulist id="defaultStartupDirList" flex="1"
                        oncommand="gComposePane.setDefaultStartupDir(this.value);">
                <menupopup class="addrbooksPopup"
                           none="&showAsDefaultLast.label;"
                           alladdressbooks="true"
                           mailinglists="true"/>
              </menulist>
            </hbox>