diff --git a/src/xmessage.cpp b/src/xmessage.cpp
index 0d6ad99..621d838 100644
--- a/src/xmessage.cpp
+++ b/src/xmessage.cpp
@@ -12,6 +12,7 @@
 #include <sstream>
 #include <string>
 #include <utility>
+#include <ciso646>
 
 #include "xeus/xguid.hpp"
 #include "xeus/xmessage.hpp"