diff --git a/common/fltk/src/Fl.cxx b/common/fltk/src/Fl.cxx
index b0cb020..134e4d0 100644
--- a/common/fltk/src/Fl.cxx
+++ b/common/fltk/src/Fl.cxx
@@ -86,6 +86,7 @@
 //
 #if defined(__APPLE__) || defined(FL_DOXYGEN)
 const char *Fl_Mac_App_Menu::about = "About ";
+const char *Fl_Mac_App_Menu::copyright = NULL;
 const char *Fl_Mac_App_Menu::print = "Print Front Window";
 const char *Fl_Mac_App_Menu::services = "Services";
 const char *Fl_Mac_App_Menu::hide = "Hide ";