diff --git a/setup.sh b/setup.sh
index fe0c154..1eeeb5c 100644
--- a/setup.sh
+++ b/setup.sh
@@ -65,7 +65,7 @@ function get_parts () {
 }
 
 function we_have_exactly_one_part () {
-    declare parttype parts_list parts_count
+    local parttype parts_list parts_count
     parttype="${1:?}"
     parts_list="${2:?}"
     parts_count="$(wc -l <<<"${parts_list}")"