As described in many blog posts and in the scientific literature, exploits for software vulnerabilities are often engineered on the basis of patches. For example, "Microsoft Patch Tuesday" is often followed by "Exploit Wednesday" during which yet unpatched systems become vulnerable to patch-based exploits. Part of the patch engineering includes the identification of the vulnerable binary code by means of reverse-engineering tools and diffing add-ons. In this article we present a feedback-driven compiler tool flow that iteratively transforms code until diffing tools become ineffective enough to close the "Exploit Wednesday" window of opportunity. We demonstrate the tool's effectiveness on a set of real-world patches and against the latest version of BinDiff.