diff --git a/.Rbuildignore b/.Rbuildignore
index a8088dea97..5e593e3381 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -2,6 +2,7 @@
 ^\.Rproj\.user$
 ^.github.*
 ^.vscode.*
+^.cache.*
 tools/torchgen/.Rbuildignore
 ^README\.Rmd$
 ^_pkgdown\.yml$
@@ -24,6 +25,8 @@ tools/torchgen/.Rbuildignore
 ^build\-lantern.*$
 ^src/Makevars$
 ^lib/.*lantern
+compile_flags.*
+mnist-r.*
 
 # remove vignettes from CRAN
 # ^vignettes/distributions\.Rmd
diff --git a/R/device.R b/R/device.R
index a38d4429a7..f52b48fd97 100644
--- a/R/device.R
+++ b/R/device.R
@@ -51,7 +51,7 @@ Device <- R7Class(
 )
 
 #' @export
-as.character.torch_device <- function(x) {
+as.character.torch_device <- function(x, ...) {
   chr <- x$type
   if (!is.null(x$index)) {
     chr <- paste0(chr, ":", x$index)