diff --git a/R/Domain_methods.R b/R/Domain_methods.R
index f73a6f37..83d3dab6 100644
--- a/R/Domain_methods.R
+++ b/R/Domain_methods.R
@@ -46,7 +46,7 @@ domain_test = function(param, values) isTRUE(domain_check(param, values))
 #' This should be the number of discrete possible levels for discrete type [`Domain`]s such as [`p_int()`] or [`p_fct()`], and
 #' `Inf` for continuous or untyped parameters.
 #'
-#' @param x (`Domain`).
+#' @param param (`Domain`).
 #' @return `numeric`.
 #' @keywords internal
 #' @export
diff --git a/R/ParamSet.R b/R/ParamSet.R
index 576d2698..529338dd 100644
--- a/R/ParamSet.R
+++ b/R/ParamSet.R
@@ -240,6 +240,7 @@ ParamSet = R6Class("ParamSet",
       if (is.data.frame(x)) x = as.list(x)
       assert_list(x, names = "unique")
       trafos = private$.trafos[names(x), .(id, trafo), nomatch = 0]
+      value = NULL  # static checks
       trafos[, value := x[id]]
       if (nrow(trafos)) {
         transformed = pmap(trafos, function(id, trafo, value) trafo(value))
@@ -547,6 +548,7 @@ ParamSet = R6Class("ParamSet",
       x = t(x)
       params = private$.params[rownames(x), on = "id"]
       params$result = list()
+      result = NULL  # static checks
       params[, result := list(as.list(as.data.frame(t(matrix(domain_qunif(recover_domain(.SD, .BY), x[id, ]), nrow = .N))))),
         by = c("cls", "grouping")]
       as.data.table(set_names(params$result, params$id))
@@ -750,7 +752,7 @@ ParamSet = R6Class("ParamSet",
         # convert all integer params really to storage type int, move doubles to within bounds etc.
         # solves issue #293, #317
         nontt = discard(xs, inherits, "TuneToken")
-
+        values = special_vals = NULL  # static checks
         sanitized = set(private$.params[names(nontt), on = "id"], , "values", list(nontt))[
           !pmap_lgl(list(special_vals, values), has_element),
           .(id, values = domain_sanitize(recover_domain(.SD, .BY), values)), by = c("cls", "grouping")]
diff --git a/R/zzz.R b/R/zzz.R
index 889ab788..3b1dc802 100644
--- a/R/zzz.R
+++ b/R/zzz.R
@@ -11,7 +11,7 @@
 # data.table-variables to announce:
 # .init_given, .trafo
 
-utils::globalVariables(c("J", "id", "original_id", "owner_ps_index", ".tags", "tag", ".trafo", ".", "cargo", "default", "cls", "cond", "on"))
+utils::globalVariables(c("J", "id", "original_id", "owner_ps_index", ".tags", "tag", ".trafo", "trafo", ".", "cargo", "default", "cls", "cond", "on"))
 
 .onLoad = function(libname, pkgname) { # nolint
   # nocov start
diff --git a/man/domain_nlevels.Rd b/man/domain_nlevels.Rd
index a74c2cf6..e4d1511e 100644
--- a/man/domain_nlevels.Rd
+++ b/man/domain_nlevels.Rd
@@ -7,7 +7,7 @@
 domain_nlevels(param)
 }
 \arguments{
-\item{x}{(\code{Domain}).}
+\item{param}{(\code{Domain}).}
 }
 \value{
 \code{numeric}.