diff --git a/src/TimeoutException.php b/src/TimeoutException.php
index 18ea72f..6f157ce 100644
--- a/src/TimeoutException.php
+++ b/src/TimeoutException.php
@@ -10,6 +10,13 @@ class TimeoutException extends RuntimeException
 
     public function __construct($timeout, $message = null, $code = null, $previous = null)
     {
+        // Preserve compatibility with our former signature, but avoid invalid arguments for the parent constructor:
+        if ($message === null) {
+            $message = '';
+        }
+        if ($code === null) {
+            $code = 0;
+        }
         parent::__construct($message, $code, $previous);
 
         $this->timeout = $timeout;