diff --git a/main.go b/main.go
index decee81..23a81e5 100644
--- a/main.go
+++ b/main.go
@@ -113,6 +113,7 @@ func handleIndex(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
 	w.Header().Set("Referrer-Policy", "no-referrer")
 	w.Header().Set("X-Frame-Options", "DENY")
 	w.Header().Set("X-Xss-Protection", "1; mode=block")