Or increase reliability, that has been already suggested, because most often "fiabilité" is "reliability", I just wanted to add a note about the Termium entry:
- the normal and natural increase in reliability at start of existence of a product or infrastructure is what is called "burn-in"; this simply means that obvious and almost unavoidable reasons for failure appear first and are fixed for good; this is also called in French "déverminage" and in this meaning Termium is right
- the increase in reliability that can be acquired later in the normal life of an equipment or system (at a point where its intrinsic reliability or components is rather a steady value) is then a very different concept and Termium wrong there

I prefer the term "robustness" because the reliability concept is based on past experience of failures that actually happened, so it cannot be increased or decreased, whereas robustness is the supposed capacity to resist future failure causes, and this is in my opinion rather the concept meant in the original text