diff --git a/src/g_all_guis.h b/src/g_all_guis.h
index 83ba9aed7aba335364d810d65e860a8a39471361..b0bdf67ac09fac19f7cbfad7ad5b794325db1632 100644
--- a/src/g_all_guis.h
+++ b/src/g_all_guis.h
@@ -280,6 +280,8 @@ typedef struct _vslider
     t_iemgui x_gui;
     int      x_pos;
     int      x_val;
+    int      x_center;
+    int      x_thick;
     int      x_lin0_log1;
     int      x_steady;
     double   x_min;