Is it possible to use Google Container Registry as an Helm repo? I had success pushing charts to GCR, however when I try to add the repo using helm, I get an error"

Error: looks like "https://gcr.io/********" is not a valid chart repository or cannot be reached: error converting YAML to JSON: yaml: mapping values are not allowed in this context

Is that something to expect? I am doing

helm repo add reponame https://gcr.io/***** --username user-name --password *****