diff --git a/src/support/Messages.cpp b/src/support/Messages.cpp
index 3b3adce141..5d2a554d83 100644
--- a/src/support/Messages.cpp
+++ b/src/support/Messages.cpp
@@ -15,6 +15,7 @@
 #include "support/docstring.h"
 #include "support/environment.h"
 #include "support/Package.h"
+#include "support/unicode.h"
 
 #include <boost/assert.hpp>