diff --git a/library/think/debug/Html.php b/library/think/debug/Html.php
index b6be7adbe341cde1ee333eec31659e910af07e92..c4a5c86387a9bb15164a13344c3fe3b4d1dc055d 100644
--- a/library/think/debug/Html.php
+++ b/library/think/debug/Html.php
@@ -47,9 +47,9 @@ class Html
         $request     = Request::instance();
         $contentType = $response->getHeader('Content-Type');
         $accept      = $request->header('accept');
-        if (strpos($accept, 'application/json') === 0 || $request->isAjax()) {
+        if ((is_string($accept) && strpos($accept, 'application/json') === 0) || $request->isAjax()) {
             return false;
-        } elseif (!empty($contentType) && strpos($contentType, 'html') === false) {
+        } elseif (!empty($contentType) && (is_string($contentType) && strpos($contentType, 'html') === false)) {
             return false;
         }
         // 获取基本信息