diff --git a/src/lib/lists.pl b/src/lib/lists.pl
index 3d1cc6a2f..b9866e71c 100644
--- a/src/lib/lists.pl
+++ b/src/lib/lists.pl
@@ -157,11 +157,17 @@
 
 %% append(Xs0, Xs1, Xs).
 %
-% List Xs is the concatenation of Xs0 and Xs1
+% True if list Xs is the concatenation of Xs0 and Xs1
 %
 % ```
 % ?- append([1,2,3], [4,5,6], Xs).
 %    Xs = [1,2,3,4,5,6].
+% ?- append([1,2,3], [4,5,6], [1,2,3,4,5,6]).
+%    true.
+% ?- append("Scr", "yer", "Scryer").
+%    true.
+% ?- append("Scr", "yer", Xs).
+%    Xs = "Scryer".
 % ```
 append([], R, R).
 append([X|L], R, [X|S]) :- append(L, R, S).