diff --git a/developer/hooks/core.php b/developer/hooks/core.php
index 8a281b0..5116f36 100755
--- a/developer/hooks/core.php
+++ b/developer/hooks/core.php
@@ -2205,7 +2205,7 @@ function hook_theme($existing, $type, $theme, $path) {
 function hook_theme_registry_alter(&$theme_registry) {
   // Kill the next/previous forum topic navigation links.
   foreach ($theme_registry['forum_topic_navigation']['preprocess functions'] as $key => $value) {
-    if ($value = 'template_preprocess_forum_topic_navigation') {
+    if ($value == 'template_preprocess_forum_topic_navigation') {
       unset($theme_registry['forum_topic_navigation']['preprocess functions'][$key]);
     }
   }