diff --git a/libraries/core.lib.php b/libraries/core.lib.php
index e5997a5608..ef79c916d3 100644
--- a/libraries/core.lib.php
+++ b/libraries/core.lib.php
@@ -1088,7 +1088,7 @@ function PMA_safeUnserialize($data)
             case 's':
                 /* string */
                 // parse sting length
-                $strlen = intval($data[$i + 2]);
+                $strlen = intval(substr($data, $i + 2));
                 // string start
                 $i = strpos($data, ':', $i + 2);
                 if ($i === false) {
diff --git a/test/libraries/core/PMA_safeUnserialize_test.php b/test/libraries/core/PMA_safeUnserialize_test.php
index f2710c0792..f589361b93 100644
--- a/test/libraries/core/PMA_safeUnserialize_test.php
+++ b/test/libraries/core/PMA_safeUnserialize_test.php
@@ -44,6 +44,7 @@ class PMA_safeUnserialize_test extends PHPUnit_Framework_TestCase
             array('b:0;', false),
             array('O:1:"a":1:{s:5:"value";s:3:"100";}', null),
             array('O:8:"stdClass":1:{s:5:"field";O:8:"stdClass":0:{}}', null),
+            array('a:2:{i:0;s:90:"1234567890;a345678901234567890123456789012345678901234567890123456789012345678901234567890";i:1;O:8:"stdClass":0:{}}', null),
             array(serialize(array(1, 2, 3)), array(1, 2, 3)),
             array(serialize('string""'), 'string""'),
             array(serialize(array('foo' => 'bar')), array('foo' => 'bar')),