diff --git a/README.md b/README.md
index 8cebd56..33b882b 100644
--- a/README.md
+++ b/README.md
@@ -31,3 +31,6 @@ to the `imports` attribute of your `configuration.nix`, like this:
   computing resources, consider building the patched version of glibc on your
   local computer and then pushing its closure to your server. If you understand
   what I just said, you'll know what to do.
+- Be careful if you use Hydra to build your system environment.
+  [As @sandro pointed out](https://c3d2.social/@sandro/112337941452150951),
+  this may have unforeseen consequences. Thanks for the heads-up!