diff --git a/src/Task/ApiGen/ApiGen.php b/src/Task/ApiGen/ApiGen.php
index 21472eb4..f9e91531 100644
--- a/src/Task/ApiGen/ApiGen.php
+++ b/src/Task/ApiGen/ApiGen.php
@@ -125,7 +125,7 @@ protected static function asList($arg)
      * @param bool|string $val
      *   An argument to be normalized.
      * @param string $default
-     *   One of self::BOOL_YES or self::BOOK_NO if the provided value could not
+     *   One of self::BOOL_YES or self::BOOL_NO if the provided value could not
      *   deterministically be converted to a yes or no value.
      *
      * @return string