diff --git a/NAMESPACE b/NAMESPACE
index 739bf49e..45bd8402 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -15,3 +15,4 @@ importFrom(rgl,plot3d)
 importFrom(rgl,scaleMatrix)
 importFrom(rgl,text3d)
 importFrom(utils,browseURL)
+importFrom(utils,zip)
diff --git a/R/utilities.R b/R/utilities.R
index c5665cbc..cd13f165 100644
--- a/R/utilities.R
+++ b/R/utilities.R
@@ -67,6 +67,7 @@ process_lhn_name <- function(x) {
 #' @param Force whether to overwrite an existing file
 #' @param ... additional arguments passed to nat::write.neuron
 #' @export
+#' @importFrom utils zip
 downloadskeletons <- function (nl, dir, format = "swc", subdir = NULL, INDICES = names(nl), files = NULL, Force = FALSE, ...){
   if (grepl("\\.zip", dir)) {
     zip_file = dir