diff --git a/R/saveGIF.R b/R/saveGIF.R
index f8076366..de708e92 100644
--- a/R/saveGIF.R
+++ b/R/saveGIF.R
@@ -85,11 +85,9 @@ saveGIF = function(
   img.fmt = paste(img.name, ani.options('imgnfmt'), '.', file.ext, sep = '')
 
   if ((use.dev <- ani.options('use.dev'))){
-    if (is.character(ani.options('ani.dev')) &&
-        any(grepl(ani.options('ani.dev'), c("png", "bmp", "jpeg", "tiff")))){
+    if ("res" %in% names(formals(ani.dev))){
       ani.dev(file.path(tempdir(), img.fmt), width = ani.options('ani.width'),
               height = ani.options('ani.height'), res = ani.options('ani.res'))
-      # ,bg = ani.options('ani.bg')
     } else {
       ani.dev(file.path(tempdir(), img.fmt), width = ani.options('ani.width'),
               height = ani.options('ani.height'))
diff --git a/R/saveHTML.R b/R/saveHTML.R
index 07d2ee0e..14f2f81a 100644
--- a/R/saveHTML.R
+++ b/R/saveHTML.R
@@ -133,8 +133,7 @@ saveHTML = function(
   img.fmt = file.path(imgdir, paste(img.name, ani.options('imgnfmt'), '.', ani.type, sep = ''))
   ani.options(img.fmt = img.fmt)
   if ((use.dev <- ani.options('use.dev'))) {
-    if (is.character(ani.options('ani.dev')) &&
-        any(grepl(ani.options('ani.dev'), c("png", "bmp", "jpeg", "tiff")))) {
+    if ("res" %in% names(formals(ani.dev))){
       ani.dev(img.fmt, width = ani.options('ani.width'),
               height = ani.options('ani.height'), res = ani.options('ani.res'))
     } else {
diff --git a/R/saveVideo.R b/R/saveVideo.R
index e9aa4bdf..ca6bb43c 100644
--- a/R/saveVideo.R
+++ b/R/saveVideo.R
@@ -74,8 +74,7 @@ saveVideo = function(
   img.fmt = file.path(tempdir(), img.fmt)
   ani.options(img.fmt = img.fmt)
   if ((use.dev <- ani.options('use.dev'))) {
-    if (is.character(ani.options('ani.dev')) &&
-        any(grepl(ani.options('ani.dev'), c("png", "bmp", "jpeg", "tiff")))) {
+    if ("res" %in% names(formals(ani.dev))){
       ani.dev(img.fmt, width = ani.options('ani.width'),
               height = ani.options('ani.height'), res = ani.options('ani.res'))
     } else {