diff --git a/mail/components/preferences/connection.js b/mail/components/preferences/connection.js
index b072e2eed381..8cad2e208deb 100644
--- a/mail/components/preferences/connection.js
+++ b/mail/components/preferences/connection.js
@@ -39,6 +39,11 @@ var gConnectionsDialog = {
   beforeAccept: function ()
   {
     var proxyTypePref = document.getElementById("network.proxy.type");
+    if (proxyTypePref.value == 2) {
+      this.doAutoconfigURLFixup();
+      return true;
+    }
+
     if (proxyTypePref.value != 1)
       return true;
 
@@ -58,6 +63,7 @@ var gConnectionsDialog = {
         proxyPortPref.value = httpProxyPortPref.value;
       }
     }
+
     return true;
   },
   
@@ -147,17 +153,15 @@ var gConnectionsDialog = {
     pps.configureFromPAC(autoURL.value);
   },
   
-  writeAutoconfigURL: function ()
+  doAutoconfigURLFixup: function ()
   {
     var autoURL = document.getElementById("networkProxyAutoconfigURL");
+    var autoURLPref = document.getElementById("network.proxy.autoconfig_url");
     var URIFixup = Components.classes["@mozilla.org/docshell/urifixup;1"]
                              .getService(Components.interfaces.nsIURIFixup);
     try {
-      return URIFixup.createFixupURI(autoURL.value, 0).spec;
-    }
-    catch(ex) {
-    }
-    return undefined;
+      autoURLPref.value = autoURL.value = URIFixup.createFixupURI(autoURL.value, 0).spec;
+    } catch(ex) {}
   },
   
   readHTTPProxyServer: function ()
diff --git a/mail/components/preferences/connection.xul b/mail/components/preferences/connection.xul
index 4613d7da280d..2bdb7563eaa5 100644
--- a/mail/components/preferences/connection.xul
+++ b/mail/components/preferences/connection.xul
@@ -157,8 +157,7 @@
         </grid>
         <radio value="2" label="&autoTypeRadio.label;" accesskey="&autoTypeRadio.accesskey;"/>
         <hbox class="indent" flex="1" align="center">
-          <textbox id="networkProxyAutoconfigURL" flex="1" preference="network.proxy.autoconfig_url"
-                   onsynctopreference="return gConnectionsDialog.writeAutoconfigURL();"/>
+          <textbox id="networkProxyAutoconfigURL" flex="1" preference="network.proxy.autoconfig_url"/>
           <button id="autoReload" label="&reload.label;" accesskey="&reload.accesskey;"
                   oncommand="gConnectionsDialog.reloadPAC();" 
                   preference="pref.advanced.proxies.disable_button.reload"/>