Filling a gap in door surround - should I/how would I?

[RafeDonson]

There's a small gap by my door surround, where some of the masonry has fallen off. I've not noticed any ill effects - the hole doesn't go all the way through the wall. I rent, so if it goes downhill it won't cost me anything, but I was wondering if this would have any ill effect on the house/wall?

Also, how could I block it up, if I should? Ideally with something I can take off later if I need to - putty, etc? Advice appreciated.

 

[HERTS P&D]

Take a picture of it and sent it to your landlord, do not do anything! Let them sort it out, whatever you do will go against you.

Also by sending it via email means that it has a time and date of when you noticed the problem and let them know about it.

Andy