diff --git a/extern/zstr/zstr.hpp b/extern/zstr/zstr.hpp
index 438e620565..b6f8caadaf 100644
--- a/extern/zstr/zstr.hpp
+++ b/extern/zstr/zstr.hpp
@@ -11,6 +11,7 @@
 #include <zlib.h>
 
 #include <cassert>
+#include <cstdint>
 #include <fstream>
 #include <iostream>
 #include <memory>