diff --git a/nix/cache.nix b/nix/cache.nix
index 5db075d..2d57d57 100644
--- a/nix/cache.nix
+++ b/nix/cache.nix
@@ -25,7 +25,8 @@ in writeShellApplication {
 		map (d: ''
 			url=$(echo var.iso.url | packer console -var-file="${distroFile d}" -config-type=hcl2 sources/)
 			sha=$(echo var.iso.checksum | packer console -var-file="${distroFile d}" -config-type=hcl2 sources/)
-			if [ -z "$(mc ls storage/isos/cache/ | grep $sha)" ]; then
+			# shellcheck disable=SC2143
+			if [ -z "$(mc ls storage/isos/cache/ | grep "$sha")" ]; then
 				curl --retry 3 --retry-all-errors -o "cache/$sha.iso" "$url"
 				mc put "cache/$sha.iso" "storage/isos/cache/$sha.iso"
 			else