diff --git a/src/out b/src/out
index af644c1..2b006d4 100755
--- a/src/out
+++ b/src/out
@@ -13,7 +13,7 @@ cd - 1>&2 2>/dev/null
 
 crane push "$oci_dir" "$REPOSITORY:$TAG" --image-refs="$image_refs_file"
 additional_tags="$(jq -r '.params.additional_tags // ""' < "$INPUT_FILE")"
-if [ -n "$additional_tags" ]; then
+if [ -n "$additional_tags" ] || [ "$additional_tags" = 'null' ]; then
     if ! [ -r "$1/$additional_tags" ]; then
         fail "cannot open file $1/$additional_tags"
     fi