How do you find where a stored procedure is used (in other stored procedures)

I have a stored procedure which I want to refactor, in a database which has thousands of SPs. Is there a quick way of finding references to that stored procedure in other SPs so I can be sure that I'm not breaking any other code when I refactor.

In the application code I can look for calls to the SP easily enough, and I can do a text search over all the various sql files which define the SPs, but it's possible there may be some SPs in the database which may be missed that way.