diff --git a/src/GUI/new_gui.hxx b/src/GUI/new_gui.hxx
index 422503a1a..3f69cab95 100644
--- a/src/GUI/new_gui.hxx
+++ b/src/GUI/new_gui.hxx
@@ -7,6 +7,7 @@
 #include <simgear/structure/subsystem_mgr.hxx>
 #include <simgear/misc/sg_path.hxx>
 
+#include <string.h>
 #include <functional>
 #include <vector>
 #include <map>