Index: chamber.c
--- chamber.c.orig
+++ chamber.c
@@ -24,7 +24,7 @@ void labInit(w, data)
     XGCValues values;
 
     /* Create GC for walls */
-    data->WallGC = XCreateGC( dpy, DefaultRootWindow(dpy), NULL, NULL);
+    data->WallGC = XCreateGC( dpy, DefaultRootWindow(dpy), 0, NULL);
     XSetForeground( dpy, data->WallGC, data->foreground);
 
     /* Create GC for molecules */