diff --git a/man/add_relative_skill.Rd b/man/add_relative_skill.Rd
index 6c196edad..62bf180ad 100644
--- a/man/add_relative_skill.Rd
+++ b/man/add_relative_skill.Rd
@@ -7,7 +7,7 @@
 add_relative_skill(
   scores,
   compare = "model",
-  by = character(0),
+  by = NULL,
   metric = intersect(c("wis", "crps", "brier_score"), names(scores)),
   baseline = NULL
 )