diff --git a/tutorial/t4.geo b/tutorial/t4.geo
index 7a1e1c3c73dbda46f276fd1b72398ad87f82c20c..1e0b044c9c251ced9112c1b842baaa59c9c108fd 100644
--- a/tutorial/t4.geo
+++ b/tutorial/t4.geo
@@ -110,7 +110,7 @@ View "comments" {
   T3(0,0.11,0,0){"Hole"};
 };
 
-Color Grey70{ Surface{ 22 }; }
+Color Grey50{ Surface{ 22 }; }
 Color Purple{ Surface{ 24 }; }
 Color Red{ Line{ 1:14 }; }
 Color Yellow{ Line{ 15:20 }; }