diff --git a/third_party/msgpack11/msgpack11.hpp b/third_party/msgpack11/msgpack11.hpp
index 218733c9..cf0a40e6 100644
--- a/third_party/msgpack11/msgpack11.hpp
+++ b/third_party/msgpack11/msgpack11.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cstdint>
 #include <string>
 #include <vector>
 #include <map>