diff --git a/theme.inc b/theme.inc
index bd809146dfb..a20e4d4bb4e 100644
--- a/theme.inc
+++ b/theme.inc
@@ -1,7 +1,17 @@
 <?
   global $user;
+
+  ### Decode user cookie:
   if (isset($user)) $cookie = explode(":", base64_decode($user));
-  if (isset($cookie[9])) include "themes/$cookie[9]/theme.class";
+
+  ### Verify theme:
+  if (isset($cookie[9])) {
+   if (file_exists("themes/$cookie[9]/theme.class")) {
+     include "themes/$cookie[9]/theme.class";
+   }
+   else include "themes/default/theme.class";
+  }
   else include "themes/default/theme.class";
+
   $theme = new Theme();
 ?>
\ No newline at end of file