diff --git a/Sources/Parser.php b/Sources/Parser.php
index 7f779c8549..9021c04631 100644
--- a/Sources/Parser.php
+++ b/Sources/Parser.php
@@ -749,7 +749,7 @@ protected static function getCacheKey(string $string, int $input_types, int $out
 			self::$time_format,
 			// BBCode settings.
 			self::getBBCodes(),
-			Config::$modSettings['disabledBBC'],
+			Config::$modSettings['disabledBBC'] ?? '',
 			self::$enable_post_html,
 			// Smiley settings.
 			SmileyParser::loadData(self::$smiley_set),