diff --git a/models/ab_htmlmin.php b/models/ab_htmlmin.php
index 9883820..01d889e 100644
--- a/models/ab_htmlmin.php
+++ b/models/ab_htmlmin.php
@@ -13,10 +13,15 @@
  */
 class ab_htmlmin extends ab_htmlmin_parent {
 
-    protected function _fillCommonSmartyProperties( $oSmarty )
+    protected function _fillCommonSmartyProperties($oSmarty)
     {
         parent::_fillCommonSmartyProperties($oSmarty);
-        include_once dirname(__FILE__).'/smarty/plugins/outputfilter.trimwhitespace.php';
-        $oSmarty->load_filter ('output' , 'trimwhitespace');
+        $cfg = oxRegistry::getConfig();
+
+        $aPluginsDir = $oSmarty->plugins_dir;
+        $aPluginsDir[] = $cfg->getModulesDir()."/ab_htmlmin/smarty/plugins/";
+        $oSmarty->load_filter('output' , 'trimwhitespace');
+
+        $oSmarty->plugins_dir = $aPluginsDir;
     }
-}
\ No newline at end of file
+}
diff --git a/smarty/plugins/outputfilter.trimwhitespace.php b/smarty/plugins/outputfilter.trimwhitespace.php
new file mode 100644
index 0000000..62ab4e7
--- /dev/null
+++ b/smarty/plugins/outputfilter.trimwhitespace.php
@@ -0,0 +1,90 @@
+<?php
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsFilter
+ */
+
+/**
+ * Smarty trimwhitespace outputfilter plugin
+ * Trim unnecessary whitespace from HTML markup.
+ *
+ * @author   Rodney Rehm
+ *
+ * @param string $source input string
+ *
+ * @return string filtered output
+ * @todo     substr_replace() is not overloaded by mbstring.func_overload - so this function might fail!
+ */
+function smarty_outputfilter_trimwhitespace($source)
+{
+    $store = array();
+    $_store = 0;
+    $_offset = 0;
+
+    // Unify Line-Breaks to \n
+    $source = preg_replace("/\015\012|\015|\012/", "\n", $source);
+
+    // capture Internet Explorer Conditional Comments
+    if (preg_match_all('#<!--\[[^\]]+\]>.*?<!\[[^\]]+\]-->#is', $source, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER)) {
+        foreach ($matches as $match) {
+            $store[] = $match[0][0];
+            $_length = strlen($match[0][0]);
+            $replace = '@!@SMARTY:' . $_store . ':SMARTY@!@';
+            $source = substr_replace($source, $replace, $match[0][1] - $_offset, $_length);
+
+            $_offset += $_length - strlen($replace);
+            $_store ++;
+        }
+    }
+
+    // Strip all HTML-Comments
+    // yes, even the ones in <script> - see http://stackoverflow.com/a/808850/515124
+    $source = preg_replace('#<!--.*?-->#ms', '', $source);
+
+    // capture html elements not to be messed with
+    $_offset = 0;
+    if (preg_match_all('#<(script|pre|textarea)[^>]*>.*?</\\1>#is', $source, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER)) {
+        foreach ($matches as $match) {
+            $store[] = $match[0][0];
+            $_length = strlen($match[0][0]);
+            $replace = '@!@SMARTY:' . $_store . ':SMARTY@!@';
+            $source = substr_replace($source, $replace, $match[0][1] - $_offset, $_length);
+
+            $_offset += $_length - strlen($replace);
+            $_store ++;
+        }
+    }
+
+    $expressions = array(
+        // replace multiple spaces between tags by a single space
+        // can't remove them entirely, becaue that might break poorly implemented CSS display:inline-block elements
+        '#(:SMARTY@!@|>)\s+(?=@!@SMARTY:|<)#s'                            => '\1 \2',
+        // remove spaces between attributes (but not in attribute values!)
+        '#(([a-z0-9]\s*=\s*(["\'])[^\3]*?\3)|<[a-z0-9_]+)\s+([a-z/>])#is' => '\1 \4',
+        // note: for some very weird reason trim() seems to remove spaces inside attributes.
+        // maybe a \0 byte or something is interfering?
+        '#^\s+<#Ss'                                                       => '<',
+        '#>\s+$#Ss'                                                       => '>',
+    );
+
+    $source = preg_replace(array_keys($expressions), array_values($expressions), $source);
+    // note: for some very weird reason trim() seems to remove spaces inside attributes.
+    // maybe a \0 byte or something is interfering?
+    // $source = trim( $source );
+
+    $_offset = 0;
+    if (preg_match_all('#@!@SMARTY:([0-9]+):SMARTY@!@#is', $source, $matches, PREG_OFFSET_CAPTURE | PREG_SET_ORDER)) {
+        foreach ($matches as $match) {
+            $_length = strlen($match[0][0]);
+            $replace = $store[$match[1][0]];
+            $source = substr_replace($source, $replace, $match[0][1] + $_offset, $_length);
+
+            $_offset += strlen($replace) - $_length;
+            $_store ++;
+        }
+    }
+
+    return $source;
+}