diff --git a/src/Query.php b/src/Query.php
index 3debb9b6..ccf867a0 100644
--- a/src/Query.php
+++ b/src/Query.php
@@ -89,7 +89,7 @@ public static function build(array $params, $encoding = PHP_QUERY_RFC3986, bool
             throw new \InvalidArgumentException('Invalid type');
         }
 
-        $castBool = $treatBooleansAsInts ? static function ($v) { return (int) $v; } : static function ($v) { return $v ? 'true' : 'false'; };
+        $castBool = $treatBoolsAsInts ? static function ($v) { return (int) $v; } : static function ($v) { return $v ? 'true' : 'false'; };
 
         $qs = '';
         foreach ($params as $k => $v) {