diff --git a/library/Icinga/Exception/IcingaException.php b/library/Icinga/Exception/IcingaException.php
index 58e17dbd1..f3d06d159 100644
--- a/library/Icinga/Exception/IcingaException.php
+++ b/library/Icinga/Exception/IcingaException.php
@@ -79,6 +79,7 @@ class IcingaException extends Exception
     {
         $trace = array();
 
+        $index = 0;
         foreach ($exception->getTrace() as $index => $frame) {
             $trace[] = isset($frame['file'])
                 ? "#{$index} {$frame['file']}({$frame['line']}): "