diff --git a/src/lib/clpz.pl b/src/lib/clpz.pl
index 6575a32d..46618032 100644
--- a/src/lib/clpz.pl
+++ b/src/lib/clpz.pl
@@ -7173,10 +7173,6 @@ contribution_at(T, Task, Offset-Bs, Contribution) :-
             ?(Contribution) #= B*C
         ).
 
-nth1(I, Es, E) :-
-        I0 is I-1,
-        nth0(I0, Es, E).
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 %% disjoint2(+Rectangles)