diff --git a/R/DownloadModule.R b/R/DownloadModule.R
index 147b5269..8161be89 100644
--- a/R/DownloadModule.R
+++ b/R/DownloadModule.R
@@ -65,7 +65,7 @@ download_report_button_srv <- function(id,
   checkmate::assert_list(rmd_yaml_args, names = "named")
   checkmate::assert_names(
     names(rmd_yaml_args),
-    subset = c("author", "title", "date", "output", "toc"),
+    subset.of = c("author", "title", "date", "output", "toc"),
     must.include = "output"
   )
   checkmate::assert_true(rmd_yaml_args[["output"]] %in% rmd_output)
diff --git a/R/Previewer.R b/R/Previewer.R
index 41a3d913..0f5dd200 100644
--- a/R/Previewer.R
+++ b/R/Previewer.R
@@ -62,7 +62,7 @@ reporter_previewer_srv <- function(id,
   checkmate::assert_list(rmd_yaml_args, names = "named")
   checkmate::assert_names(
     names(rmd_yaml_args),
-    subset = c("author", "title", "date", "output", "toc"),
+    subset.of = c("author", "title", "date", "output", "toc"),
     must.include = "output"
   )
   checkmate::assert_true(rmd_yaml_args[["output"]] %in% rmd_output)