If the space is at the bottom, that's the same bug as you see on multiple images -- vertical-align being the solution.
Will actually do the trick in most cases... just as with the oddball gap below images people have hacked around for a decade or more. Stands to reason as inline-block is basically an IMG tag's default behavior -- You might also try bottom -- it's kind-of hit or miss.
Though really it's part of why I don't use inline-block on block level elements in all but the rarest of cases. The other part being IE7/earlier can only make inline-level elements inline-block. (kind-of)
Also, test across browsers, you'll notice that gap is probably a different size -- fun, no?
If that doesn't do the trick, you might want to look at using flex-box or sucking it up and floating things, at least as a fallback for when inline-block isn't getting the job done.