diff --git a/core/lib/GNSSCore/ObsID.hpp b/core/lib/GNSSCore/ObsID.hpp
index d0251fe4c..612e4d2fa 100755
--- a/core/lib/GNSSCore/ObsID.hpp
+++ b/core/lib/GNSSCore/ObsID.hpp
@@ -47,6 +47,7 @@
 #ifndef OBSID_HPP
 #define OBSID_HPP
 
+#include <cstdint>
 #include <iostream>
 #include <iomanip>
 #include <sstream>