diff --git a/src/PregReplace.php b/src/PregReplace.php
index 43df0da2..2c595d6f 100644
--- a/src/PregReplace.php
+++ b/src/PregReplace.php
@@ -143,6 +143,7 @@ public function filter($value)
      * Validate a pattern and ensure it does not contain the "e" modifier
      *
      * @param  string $pattern
+     * @return bool
      * @throws Exception\InvalidArgumentException
      */
     protected function validatePattern($pattern)