git branches & merge

Hi.
I have created a release_x branch to work on a new release. The branch is based
on master.
Later I needed to create a hotfix_x branch to work on a hotfix. This branch is
also based on master.

In the hotfix_x branch I needed to correct an IP address to communicate with.
After doing so, I merged the hotfix_x branch with master again and made my
deployment.

Now in the release_x branche the IP address is still the old one.
I am afraid of committing and merging my release_x branch since I think that my
newly defined IP address (now on master) will be overridden when merging.
Am I right? If yes, what is the best way to solve this?

Thanks
-fuz