diff --git a/libraries/classes/Util.php b/libraries/classes/Util.php
index e9925af3fb..9941ed1dbf 100644
--- a/libraries/classes/Util.php
+++ b/libraries/classes/Util.php
@@ -1454,11 +1454,11 @@ class Util
      * Converts a BIT type default value
      * for example, b'010' becomes 010
      *
-     * @param string $bit_default_value value
+     * @param string|null $bit_default_value value
      *
      * @return string the converted value
      */
-    public static function convertBitDefaultValue(string $bit_default_value): string
+    public static function convertBitDefaultValue(?string $bit_default_value): string
     {
         return (string) preg_replace("/^b'(\d*)'?$/", '$1', htmlspecialchars_decode((string) $bit_default_value, ENT_QUOTES), 1);
     }