diff --git a/cmd/unread/unread.go b/cmd/unread/unread.go
index d4a7806..1f2548c 100644
--- a/cmd/unread/unread.go
+++ b/cmd/unread/unread.go
@@ -94,6 +94,7 @@ func newMailCounter() *mailCounter {
 
 func (mc *mailCounter) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Access-Control-Allow-Origin", "*")
+	w.Header().Set("Content-Type", "application/json")
 	c := map[string]int{}
 	for k, v := range mc.counts {
 		if v != 0 {