diff --git a/pl/boot.yap b/pl/boot.yap
index b7d1c5b4a..31b649959 100644
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -1163,7 +1163,7 @@ throw(Ball) :-
 	    throw(Ball)
 	).
 
-'catch_ball'('$abort', _, _) :- !, fail.
+'catch_ball'('$abort', _) :- !, fail.
 % system defined throws should be ignored by used, unless the
 % user is hacking away.
 'catch_ball'(Ball, V) :-