diff --git a/testing/xpcshell/head.js b/testing/xpcshell/head.js
index 6e5707d881b..9e673670ca6 100644
--- a/testing/xpcshell/head.js
+++ b/testing/xpcshell/head.js
@@ -1073,7 +1073,7 @@ function do_get_profile() {
           prop == "ProfLDS" || prop == "TmpD") {
         return file.clone();
       }
-      throw Components.results.NS_ERROR_FAILURE;
+      return null;
     },
     QueryInterface: function(iid) {
       if (iid.equals(Components.interfaces.nsIDirectoryServiceProvider) ||