SPF entries in your domains DNS are not configured to match with Zoho & Google Gmail

SPF entries in your domains DNS are not configured to match with Zoho & Google Gmail

We do have 2 servers for one domain, so we use to have for the last 10 months the following without problems:

v=spf1 mx include:zoho.com include:_spf.google.com ~all
and today we have a warning in our zoho mail account asking to change the SPF to 

v=spf1 mx include:zoho.com ~all

What is wrong with the actual SPF? we need both services (Google Mail, and Zoho)

Thanks