diff --git a/core/imageboard/tag.php b/core/imageboard/tag.php
index 44ebdef0..db251823 100644
--- a/core/imageboard/tag.php
+++ b/core/imageboard/tag.php
@@ -98,7 +98,7 @@ class Tag
 
         // don't cache in unit tests, because the test suite doesn't
         // reset static variables but it does reset the database
-        if(!UNITTEST && array_key_exists($tag, self::$tag_id_cache)) {
+        if(!defined("UNITTEST") && array_key_exists($tag, self::$tag_id_cache)) {
             return self::$tag_id_cache[$tag];
         }