diff --git a/include/wx/gtk/private/string.h b/include/wx/gtk/private/string.h
index 8be04b483f..9721015bf2 100644
--- a/include/wx/gtk/private/string.h
+++ b/include/wx/gtk/private/string.h
@@ -36,6 +36,7 @@ private:
 // list for sorting collated strings
 // ----------------------------------------------------------------------------
 
+#include "wx/string.h"
 #include "wx/vector.h"
 #include "wx/sharedptr.h"