diff --git a/library/Icinga/Web/LessCompiler.php b/library/Icinga/Web/LessCompiler.php
index e1ec06e50..e5f8dddfa 100644
--- a/library/Icinga/Web/LessCompiler.php
+++ b/library/Icinga/Web/LessCompiler.php
@@ -116,8 +116,11 @@ class LessCompiler
      */
     public function setTheme($theme)
     {
-        Logger::debug($theme);
-        $this->theme = $theme;
+        if (is_file($theme) && is_readable($theme)) {
+            $this->theme = $theme;
+        } else {
+            Logger::error('Can\t load theme %s. Make sure that the theme exists and is readable', $theme);
+        }
         return $this;
     }