Add extra check for fix IE 11 bug

[c01nd01r]

Fixes

Related to #207

[j-d-carmichael]

https://github.com/johndcarmichael/postmatex

As the current authors have left this tool dormant for too long but my project actually depends on it, I have forked and published it as postmatex.

Looking for help if you want to come on board?

This PR is already merged into the above.