diff --git a/src/tree_gui.cpp b/src/tree_gui.cpp
--- a/src/tree_gui.cpp
+++ b/src/tree_gui.cpp
@@ -8,6 +8,7 @@
 #include "gfx_func.h"
 #include "tilehighlight_func.h"
 #include "player_func.h"
+#include "player_base.h"
 #include "command_func.h"
 #include "sound_func.h"
 #include "settings_type.h"