Emacs: XML Syntax highlighting / Font-lock-mode not working

Problem: When editing XML Files in emacs on Debian, it won't do any syntax highlighting (named font-lock-mode in emacs) for anything in the file

Reason: psgml Package installed, which is a emacs SGML major mode that kicks in when editing XML Files (as XML is a subset of SGML iirc) instead of the normal XML-mode and doesn't seem to have syntax highlighting.

Solution: Remove the psgml package: aptitude remove psgml to get back normal XML mode