diff --git a/change_log.txt b/change_log.txt
index 1a58b67e..b9778c3e 100644
--- a/change_log.txt
+++ b/change_log.txt
@@ -1,4 +1,7 @@
 ===== trunk  =====
+05.10.2011
+- bugfix of problem introduced with r4342 by replacing strlen() with isset()
+
 04.10.2011
 - bugfix assign() in plugins called in subtemplates did change value also in parent template
 - bugfix of problem introduced with r4342 on math plugin 
diff --git a/libs/sysplugins/smarty_internal_compile_private_block_plugin.php b/libs/sysplugins/smarty_internal_compile_private_block_plugin.php
index 13a1c088..5288f456 100644
--- a/libs/sysplugins/smarty_internal_compile_private_block_plugin.php
+++ b/libs/sysplugins/smarty_internal_compile_private_block_plugin.php
@@ -37,7 +37,7 @@ class Smarty_Internal_Compile_Private_Block_Plugin extends Smarty_Internal_Compi
      */
     public function compile($args, $compiler, $parameter, $tag, $function)
     {
-        if (!isset($tag[6]) || substr($tag, -5) != 'close') {
+        if (!isset($tag[5]) || substr($tag, -5) != 'close') {
             // opening tag of block plugin
             // check and get attributes
             $_attr = $this->getAttributes($compiler, $args);
diff --git a/libs/sysplugins/smarty_internal_compile_private_registered_block.php b/libs/sysplugins/smarty_internal_compile_private_registered_block.php
index f7dd74ba..9fed36c3 100644
--- a/libs/sysplugins/smarty_internal_compile_private_registered_block.php
+++ b/libs/sysplugins/smarty_internal_compile_private_registered_block.php
@@ -36,7 +36,7 @@ class Smarty_Internal_Compile_Private_Registered_Block extends Smarty_Internal_C
      */
     public function compile($args, $compiler, $parameter, $tag)
     {
-        if (!isset($tag[6]) || substr($tag,-5) != 'close') {
+        if (!isset($tag[5]) || substr($tag,-5) != 'close') {
             // opening tag of block plugin
             // check and get attributes
             $_attr = $this->getAttributes($compiler, $args);
diff --git a/libs/sysplugins/smarty_security.php b/libs/sysplugins/smarty_security.php
index 6ed96204..3d4f3189 100644
--- a/libs/sysplugins/smarty_security.php
+++ b/libs/sysplugins/smarty_security.php
@@ -364,7 +364,7 @@ class Smarty_Security {
                 return true;
             }
             // abort if we've reached root
-            if (($pos = strrpos($directory, DS)) === false || !isset($directory[2])) {
+            if (($pos = strrpos($directory, DS)) === false || !isset($directory[1])) {
                 break;
             }
             // bubble up one level