diff --git a/authparams.php b/authparams.php
index d8a013b..c2baa44 100644
--- a/authparams.php
+++ b/authparams.php
@@ -74,6 +74,8 @@ class authparams
     }
     else
     {
+      if (! array_key_exists ("PHP_AUTH_PW", $_SERVER))
+        $_SERVER["PHP_AUTH_PW"] = null;
       return array ("email"=>trim ($_SERVER["PHP_AUTH_USER"]),
                     "password"=>$_SERVER["PHP_AUTH_PW"]);
     }