diff --git a/DESCRIPTION b/DESCRIPTION
index 140a6ec9..5f98740b 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -26,7 +26,7 @@ Authors@R: c(
 URL: https://jkunst.com/highcharter/, https://github.com/jbkunst/highcharter
 BugReports: https://github.com/jbkunst/highcharter/issues
 License: MIT + file LICENSE
-RoxygenNote: 7.1.2
+RoxygenNote: 7.2.1
 Roxygen: list(markdown = TRUE)
 Encoding: UTF-8
 Depends:
@@ -51,7 +51,8 @@ Imports:
     lubridate,
     yaml,
     rlang (>= 0.1.1),
-    rjson
+    rjson,
+    methods
 Suggests:
     knitr,
     rmarkdown,
diff --git a/NAMESPACE b/NAMESPACE
index 9a0dedcc..213fd911 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -229,6 +229,7 @@ importFrom(igraph,vertex_attr)
 importFrom(jsonlite,toJSON)
 importFrom(lubridate,is.Date)
 importFrom(magrittr,"%>%")
+importFrom(methods,is)
 importFrom(purrr,map)
 importFrom(purrr,map2)
 importFrom(purrr,map_chr)
diff --git a/R/highcharts-api-helpers.R b/R/highcharts-api-helpers.R
index 30ebc1c6..253d73e2 100644
--- a/R/highcharts-api-helpers.R
+++ b/R/highcharts-api-helpers.R
@@ -346,10 +346,11 @@ hc_motion <- function(hc, enabled = TRUE, startIndex = 0, ...) {
   hc
 }
 
+#' @importFrom methods is
 #' @rdname hc_add_yAxis
 #' @export
 hc_yAxis_multiples <- function(hc, ...) {
-  if (length(list(...)) == 1 & class(list(...)[[1]]) == "hc_axis_list") {
+  if (length(list(...)) == 1 & is(list(...)[[1]])[[1]] == "hc_axis_list") {
     hc$x$hc_opts$yAxis <- list(...)[[1]]
   } else {
     hc$x$hc_opts$yAxis <- list(...)
@@ -360,7 +361,7 @@ hc_yAxis_multiples <- function(hc, ...) {
 #' @rdname hc_add_yAxis
 #' @export
 hc_xAxis_multiples <- function(hc, ...) {
-  if (length(list(...)) == 1 & class(list(...)[[1]]) == "hc_axis_list") {
+  if (length(list(...)) == 1 & is(list(...)[[1]])[[1]] == "hc_axis_list") {
     hc$x$hc_opts$xAxis <- list(...)[[1]]
   } else {
     hc$x$hc_opts$xAxis <- list(...)
@@ -371,7 +372,7 @@ hc_xAxis_multiples <- function(hc, ...) {
 #' @rdname hc_add_yAxis
 #' @export
 hc_zAxis_multiples <- function(hc, ...) {
-  if (length(list(...)) == 1 & class(list(...)[[1]]) == "hc_axis_list") {
+  if (length(list(...)) == 1 & is(list(...)[[1]])[[1]] == "hc_axis_list") {
     hc$x$hc_opts$zAxis <- list(...)[[1]]
   } else {
     hc$x$hc_opts$zAxis <- list(...)