diff --git a/robots-txt-cache.php b/robots-txt-cache.php
index ef4a6aa49e57abab2230aee6dafcaa3b1b4d5d48..5cab1e8642f478cdd091657ea0587e6eaf71456f 100644
--- a/robots-txt-cache.php
+++ b/robots-txt-cache.php
@@ -8,7 +8,7 @@
  */
 
 function ai_robots_txt_add_cache_headers() {
-    header("Cache-Control", "max-age=86400");
+    header("Cache-Control: max-age=86400");
 }
 
 add_action('do_robotstxt', 'ai_robots_txt_add_cache_headers');