Whilst I disapprove of your use of the word "just", which I am strongly of the opinion should be banned in engineering circles...

I have done something similar, albeit in a different context, to fix the behaviour of a poorly performing SQL query embedded in a binary for which the source code was not easily available (as in: it turned out that the version in source control wasn't the version running in production and it would have been quite a lot of work to reverse engineer the production version and retrofit its changes back to the source - and, yes, this is as bad as you think it is).

When I initially suggesting monkey patching the binary there was all manner of screaming and objections from my colleagues but they were eventually forced to concede that it was the pragmatic and sensible thing to do.