diff --git a/vncviewer/parameters.h b/vncviewer/parameters.h
index 59909d1..5a9170e 100644
--- a/vncviewer/parameters.h
+++ b/vncviewer/parameters.h
@@ -39,6 +39,7 @@
 
 #ifdef HAVE_FLTK_FULLSCREEN
 extern rfb::BoolParameter fullScreen;
+extern rfb::BoolParameter maximize;
 #ifdef HAVE_FLTK_FULLSCREEN_SCREENS
 extern rfb::BoolParameter fullScreenAllMonitors;
 #endif // HAVE_FLTK_FULLSCREEN_SCREENS