diff --git a/doc/showcase/classlayer.dot b/doc/showcase/classlayer.dot
index 90d554e7..a956df38 100644
--- a/doc/showcase/classlayer.dot
+++ b/doc/showcase/classlayer.dot
@@ -2,6 +2,7 @@ digraph G {
 fontname="Helvetica,Arial,sans-serif"
 node [fontname="Helvetica,Arial,sans-serif"]
 edge [fontname="Helvetica,Arial,sans-serif"]
+splines=curved
 rankdir="LR"
 node [shape=box, height=0.25]
 edge [fontsize=8 arrowsize=0.5]