diff --git a/mail/base/content/aboutDialog.xul b/mail/base/content/aboutDialog.xul
index 3bdc36f25a73..14147a46891f 100644
--- a/mail/base/content/aboutDialog.xul
+++ b/mail/base/content/aboutDialog.xul
@@ -49,7 +49,12 @@
 <dialog xmlns:html="http://www.w3.org/1999/xhtml"
         xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
         id="aboutDialog"
+#ifdef XP_MACOSX
+        buttons="extra2"
+        align="end"
+#else
         buttons="accept,extra2"
+#endif
         onload="onLoad();"
         title="&aboutDialog.title;" creditslabel="&credits;" aboutlabel="&aboutLink;" versionlabel="&aboutVersion;"
         style="width: 299px; height: 330px;"> 
diff --git a/mail/base/content/mailWindowOverlay.js b/mail/base/content/mailWindowOverlay.js
index b4213c9b8bd7..23d50cc5a0d7 100644
--- a/mail/base/content/mailWindowOverlay.js
+++ b/mail/base/content/mailWindowOverlay.js
@@ -2451,3 +2451,12 @@ function loadThrobberUrl(urlPref)
         messenger.launchExternalURL(url);  
     } catch (ex) {}
 }
+
+function openAboutDialog()
+{
+#ifdef XP_MACOSX
+  window.open("chrome://messenger/content/aboutDialog.xul", "About", "centerscreen,chrome,resizable=no");
+#else
+  window.openDialog("chrome://messenger/content/aboutDialog.xul", "About", "modal,centerscreen,chrome,resizable=no");
+#endif
+}
diff --git a/mail/base/content/mailWindowOverlay.xul b/mail/base/content/mailWindowOverlay.xul
index a319ce5a95a0..55f45a4b3e5d 100644
--- a/mail/base/content/mailWindowOverlay.xul
+++ b/mail/base/content/mailWindowOverlay.xul
@@ -1695,7 +1695,7 @@
           <menuseparator id="menu_HelpAboutSeparator"/>
           <menuitem id="aboutName" accesskey="&aboutCmd.accesskey;"
                     label="&aboutCmd.label;"
-                    oncommand="window.openDialog('chrome://messenger/content/aboutDialog.xul', 'About', 'modal,centerscreen,chrome,resizable=no');"/>
+                    oncommand="openAboutDialog();"/>
         </menupopup>
       </menu>