diff --git a/prism-examples/dice/two_dice_knuth.pm b/prism-examples/dice/two_dice_knuth.pm
index 9591bb9d..a3e44855 100644
--- a/prism-examples/dice/two_dice_knuth.pm
+++ b/prism-examples/dice/two_dice_knuth.pm
@@ -1,3 +1,5 @@
+// optimal program for the sum of two dice
+
 dtmc
 
 module sum_of_two_dice