diff --git a/library/think/template/taglib/Cx.php b/library/think/template/taglib/Cx.php
index af7a54c8..31e0698d 100644
--- a/library/think/template/taglib/Cx.php
+++ b/library/think/template/taglib/Cx.php
@@ -278,7 +278,7 @@ class Cx extends Taglib
      */
     public function tagCase($tag, $content)
     {
-        $value = !empty($tag['expression']) ? $tag['expression'] : $tag['value'];
+        $value = isset($tag['expression']) ? $tag['expression'] : $tag['value'];
         $flag  = substr($value, 0, 1);
         if ('$' == $flag || ':' == $flag) {
             $value = $this->autoBuildVar($value);