How do you open Messages with Command+M on OS X Yosemite?

Before updating to OS X Yosemite, I was able to open Messages with Command+M regardless of which current app was active. I would be on Safari and could press Command+M to open Messages. Since updating to Yosemite, this doesn't work for me anymore and pressing Command+M only minimizes my Safari window. I looked in the System Preferences > Keyboard > Shortcuts and couldn't find any options to have this setting.

Any ideas guys?

Thanks in advance.