diff --git a/R/plot_to_gtable.R b/R/plot_to_gtable.R
index e81711a..1df14f6 100644
--- a/R/plot_to_gtable.R
+++ b/R/plot_to_gtable.R
@@ -22,9 +22,9 @@ plot_to_gtable <- function(plot){
     else {
       # we convert the captured plot or output plot into a grob
       # to be safe, we have to save and restore the current graphics device
-      cur_dev <- dev.cur()
+      cur_dev <- grDevices::dev.cur()
       tree <- grid::grid.grabExpr(gridGraphics::grid.echo(plot))
-      dev.set(cur_dev)
+      grDevices::dev.set(cur_dev)
 
       u <- grid::unit(1, "null")
       gt <- gtable::gtable_col(NULL, list(tree), u, u)
@@ -40,7 +40,7 @@ plot_to_gtable <- function(plot){
     ## so to be absolutely sure, we also save the previous device and then restore it.
 
     # save currently active device
-    cur_dev <- dev.cur()
+    cur_dev <- grDevices::dev.cur()
     # open NULL pdf device
     grDevices::pdf(NULL)
     # convert plot to grob
@@ -48,7 +48,7 @@ plot_to_gtable <- function(plot){
     # close pdf device
     grDevices::dev.off()
     # restore previously active device
-    dev.set(cur_dev)
+    grDevices::dev.set(cur_dev)
 
     plot
   }
diff --git a/R/save.R b/R/save.R
index 3348cfe..f5fd566 100644
--- a/R/save.R
+++ b/R/save.R
@@ -28,7 +28,7 @@ ggsave <- function(filename, plot = ggplot2::last_plot(), device = NULL, path =
   # match ggsave_args to args provided
   args <- as.list(match.call())
   args[[1]] <- NULL # remove the function call
-  args <- args[na.omit(match(ggsave_args, names(args)))] # remove other args
+  args <- args[stats::na.omit(match(ggsave_args, names(args)))] # remove other args
 
   args_dotdotdot <- list(...)
 
diff --git a/R/setup.R b/R/setup.R
index 1e924d8..c0f42c0 100644
--- a/R/setup.R
+++ b/R/setup.R
@@ -6,5 +6,3 @@
   # switch the default theme to theme_cowplot
   ggplot2::theme_set(theme_cowplot())
 }
-
-.pt <- 1 / 0.352777778 # from ggplot2, file aaa-constants.r
diff --git a/man/ggsave.Rd b/man/ggsave.Rd
index 98d2bf3..4462bbe 100644
--- a/man/ggsave.Rd
+++ b/man/ggsave.Rd
@@ -38,5 +38,5 @@ specifying dimensions in pixels.}
 This function should behave just like \code{ggsave} from ggplot2,
 with the main difference being that by default it doesn't use the Dingbats
 font for pdf output. If you ever have trouble with this function, you can
-try using \code{ggplot2::ggsave()} instead.
+use \code{ggplot2::ggsave()} instead.
 }