diff --git a/support/download/helpers b/support/download/helpers
index 823e4d2f91..5ed9078287 100755
--- a/support/download/helpers
+++ b/support/download/helpers
@@ -59,7 +59,7 @@ mk_tar_gz() {
     LC_ALL=C sort <"${tmp}.list" >"${tmp}.sorted"
 
     # Create POSIX tarballs, since that's the format the most reproducible
-    tar cf - --transform="s#^\./#${base_dir}/#S" \
+    ${TAR} cf - --transform="s#^\./#${base_dir}/#S" \
              --numeric-owner --owner=0 --group=0 --mtime="${date}" \
              --format=posix --pax-option="${pax_options}" --mode='go=u,go-w' \
              -T "${tmp}.sorted" >"${tmp}.tar"
@@ -78,7 +78,7 @@ post_process_unpack() {
     local one_file
 
     mkdir "${dest}"
-    tar -C "${dest}" --strip-components=1 -xzf "${tarball}"
+    ${TAR} -C "${dest}" --strip-components=1 -xzf "${tarball}"
     one_file="$(find "${dest}" -type f -print0 |LC_ALL=C sort -z |sed 's/\x0.*//')"
     touch -r "${one_file}" "${dest}.timestamp"
 }