diff --git a/www/moduserinfo.php3 b/www/moduserinfo.php3
index 879067f5171836b57a75a8b5a48a79832596ce87..ab8c3f7f5f071327f841964fcfcfe836084c4221 100644
--- a/www/moduserinfo.php3
+++ b/www/moduserinfo.php3
@@ -293,7 +293,8 @@ function SPITFORM($formfields, $errors)
 	    # Planetlab bit. This should really be a drop down menu of the
 	    #                choices.
             #
-	    if ($formfields["user_interface"] == TBDB_USER_INTERFACE_PLAB) {
+	    if (isset($formfields["user_interface"]) &&
+		$formfields["user_interface"] == TBDB_USER_INTERFACE_PLAB) {
 		$checked = "checked";
 	    } else {
 		$checked = "";