diff --git a/index.php b/index.php
index dbe285f..938a49b 100644
--- a/index.php
+++ b/index.php
@@ -120,6 +120,11 @@ $sourceFactoryOptions = array();
 if (isset($min_serveOptions['minApp']['noMinPattern'])) {
     $sourceFactoryOptions['noMinPattern'] = $min_serveOptions['minApp']['noMinPattern'];
 }
+
+if (isset($min_serveOptions['minApp']['allowDirs'])) {
+   $sourceFactoryOptions['allowDirs'] = $min_serveOptions['minApp']['allowDirs'];
+}
+
 $sourceFactory = new Minify_Source_Factory($env, $sourceFactoryOptions, $cache);
 
 $controller = call_user_func($min_factories['controller'], $env, $sourceFactory);
diff --git a/lib/Minify/Source/Factory.php b/lib/Minify/Source/Factory.php
index 8b41e55..c65ce6d 100644
--- a/lib/Minify/Source/Factory.php
+++ b/lib/Minify/Source/Factory.php
@@ -110,6 +110,20 @@ class Minify_Source_Factory {
         return $realpath;
     }
 
+    /**
+     * turn windows-style slashes into unix-style,
+     * remove trailing slash
+     * and lowercase drive letter
+     *
+     * @param string $path absolute path
+     *
+     * @return string
+     */
+    public function getNormalizedPath($path)
+    {
+        return lcfirst(rtrim(str_replace('\\', '/', $path), '/'));
+    }
+
     /**
      * @param mixed $spec
      *
@@ -139,12 +153,17 @@ class Minify_Source_Factory {
         }
 
         if ($this->options['checkAllowDirs']) {
+            $inAllowedDir = false;
             foreach ((array)$this->options['allowDirs'] as $allowDir) {
-                if (strpos($spec['filepath'], $allowDir) !== 0) {
-                    throw new Minify_Source_FactoryException("File '{$spec['filepath']}' is outside \$allowDirs."
-                        . " If the path is resolved via an alias/symlink, look into the \$min_symlinks option.");
+                if (strpos($this->getNormalizedPath($spec['filepath']), $this->getNormalizedPath($allowDir)) === 0) {
+                    $inAllowedDir = true;
                 }
             }
+
+            if (!$inAllowedDir) {
+                throw new Minify_Source_FactoryException("File '{$spec['filepath']}' is outside \$allowDirs."
+                    . " If the path is resolved via an alias/symlink, look into the \$min_symlinks option.");
+            }
         }
 
         $basename = basename($spec['filepath']);