diff --git a/advagg.install b/advagg.install
index 8f76c30..b8a507e 100644
--- a/advagg.install
+++ b/advagg.install
@@ -12,6 +12,28 @@ function advagg_enable() {
   // Make sure the advagg_get_root_files_dir() function is available.
   drupal_load('module', 'advagg');
 
+  // Make sure permissions for dirs are correct. Needed if installed via drush.
+  list($css_path, $js_path) = advagg_get_root_files_dir()
+  $stat_public = stat('public://');
+  $stat_css = stat($css_path[0]);
+  $stat_js = stat($js_path[0]);
+  if (isset($stat_public['uid']))
+    if (isset($stat_css['uid']) && $stat_public['uid'] != $stat_css['uid']) {
+      @chown($css_path[0], $stat_public['uid']);
+    }
+    if (isset($stat_js['uid']) && $stat_public['uid'] != $stat_js['uid']) {
+      @chown($stat_js[0], $stat_public['uid']);
+    }
+  }
+  if (isset($stat_public['gid']))
+    if (isset($stat_css['gid']) && $stat_public['gid'] != $stat_css['gid']) {
+      @chgrp($css_path[0], $stat_public['gid']);
+    }
+    if (isset($stat_js['uid']) && $stat_public['gid'] != $stat_js['gid']) {
+      @chgrp($stat_js[0], $stat_public['gid']);
+    }
+  }
+
   // Make sure the advagg_flush_all_cache_bins() function is available.
   module_load_include('inc', 'advagg', 'advagg');
   module_load_include('inc', 'advagg', 'advagg.cache');