diff --git a/pypprof/net_http.py b/pypprof/net_http.py
index da38f77..04ef141 100644
--- a/pypprof/net_http.py
+++ b/pypprof/net_http.py
@@ -84,7 +84,7 @@ def index(self):
 
         self.send_response(200)
         self.send_header("X-Content-Type-Options", "nosniff")
-        self.send_header("Content-Type", "text/plain; charset=utf-8")
+        self.send_header("Content-Type", "text/html; charset=utf-8")
         self.end_headers()
         self.wfile.write(body.encode("utf-8"))