diff --git a/src/Response.php b/src/Response.php
index 92a3ad5..396ce9f 100644
--- a/src/Response.php
+++ b/src/Response.php
@@ -336,7 +336,7 @@ public function json($body, int $flags = 0): Response
     {
         $body = json_encode($body, $flags);
 
-        if (!$this->get("Content-Type")) {
+        if ($this->get("Content-Type") != "application/json") {
             $this->type("json");
         }