diff --git a/lib/SimpleSAML/Auth/TimeLimitedToken.php b/lib/SimpleSAML/Auth/TimeLimitedToken.php
index b5f3c60e65783fd400aaf935423e3c5d85f449d2..74e9cf44d9dacb696aa69b461233159d84eafd07 100644
--- a/lib/SimpleSAML/Auth/TimeLimitedToken.php
+++ b/lib/SimpleSAML/Auth/TimeLimitedToken.php
@@ -71,7 +71,7 @@ class TimeLimitedToken
             $time = time();
         }
         // a secret salt that should be randomly generated for each installation
-        return sha1(floor(($time - $offset) / ($this->lifetime + $this->skew)).':'.$this->secretSalt);
+        return sha1($offset.':'.floor(($time - $offset) / ($this->lifetime + $this->skew)).':'.$this->secretSalt);
     }