diff --git a/library/think/Hook.php b/library/think/Hook.php
index a69ce546..c320888c 100644
--- a/library/think/Hook.php
+++ b/library/think/Hook.php
@@ -32,12 +32,11 @@ class Hook
 
         if (is_array($behavior) && !is_callable($behavior)) {
             if (!array_key_exists('_overlay', $behavior) || !$behavior['_overlay']) {
-                unset($behavior['_overlay']);
                 self::$tags[$tag] = array_merge(self::$tags[$tag], $behavior);
             } else {
-                unset($behavior['_overlay']);
                 self::$tags[$tag] = $behavior;
             }
+            unset($behavior['_overlay']);
         } elseif ($first) {
             array_unshift(self::$tags[$tag], $behavior);
         } else {