diff --git a/toolkit/content/widgets/preferences.xml b/toolkit/content/widgets/preferences.xml
index 749df11173d..0d9da8c5b49 100644
--- a/toolkit/content/widgets/preferences.xml
+++ b/toolkit/content/widgets/preferences.xml
@@ -370,7 +370,7 @@
               event.initEvent("syncfrompreference", true, true);
               var f = new Function ("event", 
                                     aElement.getAttribute("onsyncfrompreference"));
-              rv = f(event);
+              rv = f.call(aElement, event);
             }
             catch (e) {
               Components.utils.reportError(e);
@@ -419,7 +419,7 @@
               event.initEvent("synctopreference", true, true);
               var f = new Function ("event", 
                                     aElement.getAttribute("onsynctopreference"));
-              var rv = f(event);
+              var rv = f.call(aElement, event);
               if (rv !== undefined) 
                 return rv;
             }