That's actually one rule which applies to multiple targets. If you run without parallelism (the default, -j1), it'll work fine, since make will run the rule fo

That's actually one rule which applies to multiple targets. If you run without parallelism (the default, -j1), it'll work fine, since make will run the rule for one target, and then when it comes to the second one, make will notice that it's already up-to-date (based on file timestamp). If you run with -j4 or something, it make will likely run the rule twice, simultaneously. That may or may not be a bad problem depending on how the rule writes the output file. EDIT: man I must have really rushed reading your post... as you say, this does appear to be a heuristic for GNU Make when it's a pattern rule. clearly make is tricky and I end up learning stuff every time I use make...