diff --git modules/openid/openid.inc modules/openid/openid.inc
index e820cd6..c9bcd6c 100644
--- modules/openid/openid.inc
+++ modules/openid/openid.inc
@@ -687,7 +687,9 @@ function openid_extract_ax_values($values, $uris) {
  * Determine the available math library GMP vs. BCMath, favouring GMP for performance.
  */
 function _openid_get_math_library() {
-  $library = &drupal_static(__FUNCTION__);
+  // Not drupal_static(), because a function is not going to disappear and
+  // change the output of this under any circumstances.
+  static $library;
 
   if (empty($library)) {
     if (function_exists('gmp_add')) {