diff --git a/includes/registry.inc b/includes/registry.inc
index c0039ef9f887d8428858e701b4b52c622f4782c5..263f8ae8afcfb75537c40352febc2d42f76a40f8 100644
--- a/includes/registry.inc
+++ b/includes/registry.inc
@@ -229,9 +229,6 @@ function _bootstrap_process_theme_registry(array &$registry, $themes) {
         // File to be included by core's theme function when a theme hook is
         // invoked.
         if (isset($registry[$hook])) {
-          if (!isset($registry[$hook][$phase_key])) {
-            $registry[$hook][$phase_key] = array();
-          }
           if (!isset($registry[$hook]['includes'])) {
             $registry[$hook]['includes'] = array();
           }
@@ -252,6 +249,11 @@ function _bootstrap_process_theme_registry(array &$registry, $themes) {
 
       // Iterate over each registered hook.
       foreach ($registry as $hook => $info) {
+        // Ensure the current phase callback functions array exists.
+        if (!isset($registry[$hook][$phase_key])) {
+          $registry[$hook][$phase_key] = array();
+        }
+
         // Remove function callbacks if a template was found.
         if (isset($info['function']) && isset($info['template'])) {
           unset($registry[$hook]['function']);